Can Bronze Corydoras Be Housed with Loaches?

Do you ever find yourself arranging a community tank but worrying about compatibility between different bottom dwellers? Bronze Corydoras are gentle, peaceful fish, and many hobbyists consider adding loaches to create a lively, active aquarium environment.

Bronze Corydoras can generally be housed with loaches, provided the tank is spacious and well-decorated. Both species are bottom dwellers, but maintaining adequate hiding spots, stable water parameters, and minimal aggression ensures a harmonious coexistence.

Keeping these species together requires attention to their environment, feeding habits, and social dynamics to maintain a peaceful, healthy aquarium for both.

Understanding Bronze Corydoras Behavior

Bronze Corydoras are peaceful, small catfish that spend most of their time near the bottom of the tank. They enjoy swimming in groups, usually in schools of at least four or five. These fish are active during the day and like to explore soft substrate, which prevents injury to their sensitive barbels. They are social but shy, often hiding when the tank feels too crowded or when more aggressive species are introduced. Their diet mainly consists of sinking pellets, small live or frozen foods, and occasional vegetables. They are generally compatible with other peaceful species, but tank layout matters. Smooth decorations, gentle currents, and plenty of hiding spots help them feel safe. Water quality is essential; they thrive in slightly acidic to neutral pH and moderate temperatures. Keeping the tank clean and monitoring for stress signs ensures these fish remain active and healthy.

These fish are peaceful and require a calm environment to thrive in community tanks.

When introducing loaches, it is important to observe interactions closely. Bronze Corydoras may initially hide more, adjusting to the new tankmates. Over time, they usually adapt, forming routines alongside the loaches while still keeping their social bonds. Proper tank arrangement and hiding spots reduce stress and help both species coexist harmoniously.

Loach Compatibility Considerations

Loaches vary in temperament depending on the species, and choosing the right type matters for harmony.

Some loaches are active and may dig around the substrate aggressively, which can disturb Bronze Corydoras. Keeping multiple hiding spots, driftwood, and caves allows loaches to explore without threatening Corydoras’ space. Feeding routines also help minimize competition; providing sinking pellets and live food in separate areas keeps both species well-fed. Avoid overcrowding, as it increases stress and can lead to territorial disputes. Loaches often prefer to be in groups, which should match the Corydoras’ need for social interaction. Watching behavior over the first weeks is crucial to prevent bullying or hiding. By creating a structured and balanced environment, both species can thrive. Proper water conditions, substrate depth, and gentle filtration further support long-term health and activity for each fish. Planning the tank carefully ensures that both Bronze Corydoras and loaches remain active, safe, and healthy in a shared aquarium.

Tank Setup Tips for Bronze Corydoras and Loaches

A spacious tank with soft substrate is essential. Include hiding spots like caves or driftwood, and maintain gentle water flow to keep both species comfortable and reduce stress in the aquarium environment.

Providing a soft, sandy substrate protects Bronze Corydoras’ sensitive barbels from injury, while loaches appreciate areas to dig and explore. Hiding spots reduce territorial disputes and encourage natural behaviors for both species. Open swimming areas should also be included to allow free movement. Lighting should be moderate, as overly bright conditions may stress Corydoras, causing them to hide. Maintaining consistent water parameters, such as slightly acidic to neutral pH and stable temperatures, supports the health of all tank inhabitants. Filtration should be efficient but gentle to avoid strong currents that could disturb either species. Regular substrate cleaning prevents buildup of waste and leftover food, keeping water quality high.

Decorative elements like driftwood, plants, and caves serve dual purposes: they create hiding spaces and make the tank visually appealing. Strategic placement ensures loaches don’t dominate the bottom, letting Corydoras feel secure while remaining visible. Regular observation helps spot early signs of stress or aggression. Feeding routines should accommodate both species, placing sinking food near Corydoras while loaches can explore other areas. Balancing tank population and layout allows peaceful coexistence and healthy interactions over the long term.

Feeding Practices for Compatibility

Feed sinking pellets or small frozen foods to satisfy both species. Separate feeding areas reduce competition and ensure each fish receives enough nutrition.

Bronze Corydoras are bottom feeders and require food that reaches the substrate. Loaches also enjoy scavenging but may be faster, potentially outcompeting Corydoras if food is limited. Dividing feeding zones ensures each species gets adequate nutrition without stress. Occasional live foods or vegetables support dietary variety and enhance coloration. Feeding small amounts multiple times a day helps prevent overeating and maintains water quality. Observing how each species eats allows adjustments in portion size and timing.

Monitoring eating habits is crucial. If Corydoras appear stressed or underfed, redistribute food or adjust the feeding schedule. Loaches can dominate certain areas, so providing extra food in different tank zones helps balance intake. Varying diet with occasional treats like bloodworms or daphnia encourages natural hunting behaviors. Maintaining proper feeding routines strengthens health, reduces aggression, and supports harmonious interactions between Bronze Corydoras and loaches in shared habitats. Consistency and observation are key to keeping both species active and thriving.

Water Parameters and Maintenance

Maintain water temperature between 72°F and 79°F for both species. Keep pH around 6.5 to 7.0 and monitor ammonia, nitrite, and nitrate levels closely to prevent stress or illness.

Regular water changes of 20–25% weekly help maintain stability. Both Bronze Corydoras and loaches are sensitive to sudden fluctuations, so consistency is key for long-term health.

Social Behavior Observations

Both species are social but in different ways. Bronze Corydoras prefer schooling, while loaches often explore in small groups. Observing how they interact ensures that neither becomes dominant or overly stressed.

Breeding Considerations

Breeding Bronze Corydoras requires separate space. Loaches may disturb eggs, so a breeding tank or protected area is recommended to increase fry survival and reduce stress on adult fish.

Common Health Issues

Watch for signs of fin rot or skin infections. Both species are prone to stress-related illnesses if water quality or tank conditions are poor.

FAQ

Can Bronze Corydoras and loaches live together peacefully?
Yes, they can coexist peacefully if the tank is properly set up. Both species are bottom dwellers, but providing enough hiding spots, soft substrate, and gentle water flow is essential. Proper tank size and group numbers also help prevent stress and aggression between them.

How many loaches should I keep with Bronze Corydoras?
It’s best to keep at least three loaches together to satisfy their social behavior. For Bronze Corydoras, maintain a school of four to six fish. Balancing the number of each species helps reduce territorial disputes and ensures both feel secure in the tank.

What type of substrate is best?
Soft, sandy substrate is ideal for Bronze Corydoras since their barbels are sensitive and can be easily injured by rough gravel. Loaches also enjoy soft substrate for digging and burrowing, which allows them to exhibit natural behaviors without harming other tank inhabitants.

Do loaches bully Bronze Corydoras?
Loaches are generally not aggressive toward Corydoras, but some digging or fast movement can startle them. Proper tank layout with multiple hiding spots reduces this risk. Observing interactions after introducing loaches ensures that Corydoras are not overly stressed or hiding constantly.

How should I feed them together?
Feed sinking pellets or small frozen foods for Bronze Corydoras, placing food near the substrate. Loaches can also forage for the same food, but providing additional feeding zones prevents competition. Occasional live or vegetable treats can add variety and support overall health.

Do they need the same water conditions?
Both species prefer slightly acidic to neutral pH (6.5–7.0) and moderate temperatures (72–79°F). Maintaining stable water parameters and performing regular water changes helps prevent stress and keeps both species healthy in a shared tank.

Can they reproduce together in the same tank?
Breeding is possible, but loaches may disturb Corydoras eggs. It’s recommended to use a separate breeding tank or protected area to improve egg survival. Once hatched, fry should be moved or closely monitored to prevent accidental predation.

What tank size is recommended?
A minimum of 30 gallons is recommended for small groups of Bronze Corydoras and loaches. Larger tanks are better, as they provide more swimming space, reduce territorial disputes, and allow room for hiding spots and decorations.

How can I tell if they are stressed?
Signs of stress include hiding excessively, reduced activity, loss of appetite, or faded colors. Stress often results from overcrowding, poor water quality, or aggressive tankmates. Monitoring behavior daily allows quick intervention to correct problems before illness develops.

What decorations are best for a mixed tank?
Use driftwood, caves, and live plants to create hiding spots and separate territories. Open swimming areas allow both species to move freely without conflict. Proper decoration placement encourages natural behavior and reduces stress, keeping both Bronze Corydoras and loaches healthy.

How often should I clean the tank?
Perform weekly water changes of 20–25% and vacuum the substrate to remove uneaten food and waste. Both species are sensitive to water quality, so regular maintenance prevents stress-related illnesses and supports long-term health.

Can they share the tank with other fish?
Yes, but choose peaceful, non-aggressive tankmates. Avoid large or territorial species that could harm Corydoras or loaches. Small tetras, rasboras, or guppies often make good companions in a community tank when water parameters and space are suitable.

What are common health problems to watch for?
Fin rot, skin infections, and stress-related illnesses can affect both species. Maintaining stable water conditions, proper diet, and clean tanks helps prevent these issues. Early detection of illness ensures prompt treatment and minimizes risk to the community.

Do loaches need hiding spots more than Corydoras?
Loaches enjoy hiding but are generally more active and exploratory than Corydoras. Providing caves, driftwood, and plant cover gives loaches safe spaces while allowing Corydoras to maintain their schooling behavior without being disturbed.

Can I keep multiple loach species with Bronze Corydoras?
Yes, but monitor behavior closely. Some loach species are more active or territorial than others. Choosing compatible species and providing adequate hiding spots and feeding zones ensures a balanced, stress-free environment for all tank inhabitants.

How do I encourage natural behavior?
Provide soft substrate, hiding spots, and gentle water flow. Regular feeding routines and occasional live foods encourage foraging, digging, and schooling. Observing interactions allows you to adjust tank layout or feeding strategies to maintain harmony between Bronze Corydoras and loaches.

Is tank lighting important?
Moderate lighting is best. Too bright lighting may stress Bronze Corydoras, causing them to hide, while loaches are more tolerant. Creating shaded areas or using floating plants gives both species comfort and encourages natural behaviors throughout the day.

Can they tolerate community tank noise?
Yes, both species are relatively tolerant of activity in a well-maintained community tank. Avoid sudden disturbances or overcrowding, as excessive stress can lead to hiding, reduced appetite, or illness. Calm, stable conditions help them feel secure.

Do they need supplemental oxygen?
In most well-aerated tanks, supplemental oxygen is not necessary. Both species benefit from moderate water movement and proper filtration, which maintain oxygen levels. Avoid strong currents that could stress Bronze Corydoras or disrupt loaches’ natural digging behaviors.

What’s the ideal group size for each species?
Maintain at least four to six Bronze Corydoras and three or more loaches. Proper group sizes support social behavior, reduce stress, and allow each species to display natural habits, creating a balanced and harmonious aquarium environment.

How long do Bronze Corydoras and loaches live?
With proper care, Bronze Corydoras can live 5–8 years, while loaches vary by species, usually 8–10 years. Maintaining stable water conditions, proper diet, and stress-free environments contributes to their longevity and overall health.

How often should I observe tank interactions?
Daily observation is recommended. Watching behavior during feeding and swimming allows early detection of stress, aggression, or health issues. Quick adjustments to tank layout, feeding zones, or water conditions keep both species comfortable and thriving in the same aquarium.

Are there signs of aggression I should watch for?
Aggression is rare between these species but can occur if space is limited or hiding spots are insufficient. Look for chasing, nipping, or prolonged hiding. Adjusting tank layout and group sizes helps reduce conflicts and maintain harmony.

Can I mix different Corydoras species with loaches?
Yes, most small, peaceful Corydoras species can coexist with loaches. Ensure compatible water conditions, group sizes, and tank layout. Monitor behavior closely, especially when introducing new species, to prevent stress or dominance issues in the community tank.

What are the benefits of keeping them together?
Keeping Bronze Corydoras with loaches creates a lively, active bottom layer. They complement each other’s behavior: Corydoras school calmly, while loaches explore and dig. This combination encourages natural activity, reduces boredom, and enhances the overall dynamics of a community tank.

How do I prevent stress during introduction?
Introduce new fish gradually and monitor closely. Provide hiding spots and feed multiple areas to reduce competition. Maintaining stable water parameters and a calm environment helps both species adjust without conflict, promoting long-term peaceful coexistence.

Are there any special decorations that help?
Driftwood, caves, and dense plants create hiding spaces and define territories. Soft substrates prevent injuries, while open swimming areas allow freedom. Proper decoration placement balances exploration and safety, supporting natural behavior for both Bronze Corydoras and loaches.

Do they react differently at night?
Loaches are generally more active at night, while Bronze Corydoras remain moderately active. Providing shaded areas and hiding spots helps both species feel secure during nighttime, reducing stress and allowing natural nocturnal behaviors to emerge.

Can tank mates affect their behavior?
Yes, aggressive or overly active species can stress both Bronze Corydoras and loaches. Choose peaceful companions, maintain proper group sizes, and provide hiding spots to reduce tension. Observing interactions ensures that all tank inhabitants coexist safely and comfortably.

How do I maintain a balanced diet for both?
Feed sinking pellets for Corydoras, offer live or frozen foods for variety, and ensure loaches get enough to eat. Dividing feeding zones reduces competition. A balanced diet supports health, coloration, and activity for both species in a shared aquarium.

Is quarantine necessary before introducing loaches?
Yes, quarantining new fish prevents introducing diseases. Observe them for at least two weeks before adding them to the main tank. This protects Bronze Corydoras and maintains a healthy environment for all community members.

Can stress cause illness in both species?
Yes, stress from poor water quality, overcrowding, or aggressive tankmates can lead to infections, fin rot, or reduced immunity. Monitoring behavior and maintaining stable conditions helps prevent health issues and promotes long-term well-being.

Do they require specific tank filtration?
Gentle but effective filtration is recommended. Strong currents can stress Bronze Corydoras, while loaches prefer moderate flow. Proper filtration maintains water quality without disrupting natural behavior, supporting health and activity for both species.

How do I recognize a happy tank environment?
Fish are active, eat well, and interact naturally. Corydoras swim in schools, loaches explore freely, and both use hiding spots appropriately. Stable water conditions, balanced diet, and minimal stress indicate a healthy, harmonious aquarium for these species.

What are the risks of overcrowding?
Overcrowding increases stress, competition for food, and territorial disputes. It can lead to hiding, reduced activity, and health problems. Maintaining proper group sizes and tank space ensures both Bronze Corydoras and loaches remain comfortable and active.

Can I mix them with fast-swimming fish?
Yes, if the fast-swimming species are non-aggressive and respect bottom dwellers. Avoid species that chase or nip. Open swimming areas and adequate hiding spots help maintain peace and reduce stress for both Corydoras and loaches.

How do I ensure long-term compatibility?
Monitor behavior, maintain water quality, and provide proper feeding zones. Adequate space, hiding spots, and compatible tankmates support ongoing harmony. Consistent care and observation help both Bronze Corydoras and loaches coexist safely for many years.

Can changes in water temperature affect them?
Yes, sudden fluctuations stress both species. Keep temperature stable within the preferred range (72–79°F). Gradual adjustments, when needed, prevent shock and maintain health and activity.

How often should I test water parameters?
Test weekly for pH, ammonia, nitrites, and nitrates. Both species are sensitive to poor water quality. Early detection allows corrective action, maintaining a safe and healthy environment in the shared aquarium.

Do plants benefit their behavior?
Yes, live or artificial plants provide hiding spots and reduce stress. Plants also improve water quality and create natural territories, helping Bronze Corydoras and loaches feel secure while encouraging exploration and activity.

Are there signs of compatibility issues?
Signs include constant hiding, aggression, refusal to eat, or abnormal swimming. Observing behavior and making adjustments to tank layout, group sizes, or feeding zones helps maintain harmony and reduces stress for both species.

How important is tank size for long-term health?
Tank size is critical. A minimum of 30 gallons is needed for small groups, but larger tanks reduce stress, provide more territory, and allow natural behavior. Proper space supports activity, social interactions, and long-term health for Bronze Corydoras and loaches.

Do loaches need more hiding spots than Corydoras?
Loaches explore actively and enjoy digging, so they benefit from additional hiding spaces. Proper distribution of caves, driftwood, and plant cover ensures both species feel secure and reduces stress or territorial disputes in the tank.

Can they adapt to different water hardness?
Both species prefer soft to moderately hard water. Gradual acclimation to different hardness levels can be tolerated, but sudden changes may stress them. Consistency in water parameters promotes long-term health and stable behavior.

Is tank cleanliness more important for them than other fish?
Yes, both species are sensitive to ammonia, nitrite, and nitrate levels. Regular substrate cleaning, water changes, and proper filtration are essential to prevent stress and disease in Bronze Corydoras and loaches.

How do I manage tank mates’ impact on feeding?
Separate feeding zones and sinking pellets reduce competition. Observing mealtime ensures both Corydoras and loaches eat adequately. Adjust portions and timing as needed to maintain health and prevent stress in a community tank.

Can they live in a planted tank?
Yes, planted tanks provide hiding spots, natural territories, and reduce stress. Soft substrate and proper plant placement support both species’ behaviors, offering exploration areas and shelter for Bronze Corydoras and loaches.

Do loaches dig up plants or decorations?
Some species may dig, which can disturb plants or substrate. Using robust plants, anchored decorations, and strategic layout prevents damage while allowing loaches to express natural behavior safely.

What water flow is ideal?
Moderate water flow is best. Strong currents can stress Bronze Corydoras, while loaches prefer gentle movement for exploration. Balanced flow maintains oxygenation without disrupting natural behaviors or creating aggression in the tank.

How do I handle introducing new Corydoras or loaches?
Quarantine new fish for two weeks. Introduce them gradually, providing hiding spots and monitoring behavior. Observing interactions early prevents aggression, stress, and disease in an established tank community.

Are loaches nocturnal or diurnal?
Many loaches are more active at night, while Bronze Corydoras remain moderately active during the day. Providing shaded areas and hiding spots accommodates natural activity patterns and reduces stress for both species.

What are warning signs of aggression?
Chasing, nipping, constant hiding, or disrupted schooling indicate stress or aggression. Adjusting tank layout, group sizes, or feeding areas can help restore harmony and reduce tension between Bronze Corydoras and loaches.

Can stress affect breeding?
Yes, stressed Corydoras may not spawn, and loaches may disturb eggs. Providing a calm, stable environment, hiding spots, and proper water parameters encourages natural breeding behavior.

Do they interact differently with different loach species?
Yes, some loaches are more active or territorial. Observing behavior after introduction ensures compatibility. Adjusting hiding spots, group sizes, and feeding zones helps maintain peace in a mixed-species tank.

Is regular observation necessary?
Yes, daily monitoring detects stress, illness, or aggression early. Quick adjustments to tank conditions, layout, or feeding routines maintain health and harmony for Bronze Corydoras and loaches.

Can they tolerate aquarium noise or vibrations?
Moderate activity is fine, but sudden noise or vibrations may startle them. Minimizing disturbances and maintaining a calm environment supports natural behavior and reduces stress.

Do they need specific lighting schedules?
Moderate, consistent lighting supports natural behavior. Corydoras prefer shaded areas, while loaches tolerate light better. A regular day-night cycle helps both species feel secure and encourages normal activity patterns.

Are there seasonal care considerations?
Yes, maintaining stable temperature, water parameters, and feeding routines is important year-round. Avoid sudden changes, especially in winter or summer, to prevent stress or illness.

How can I balance tank activity?
Provide enough open swimming areas, hiding spots, and enrichment. Feeding routines and group sizes also help balance activity, allowing both Bronze Corydoras and loaches to express natural behaviors without conflict.

Do they need a varied diet?
Yes, sinking pellets, live or frozen foods, and occasional vegetables support health, growth, and coloration. Varying diet encourages natural foraging and keeps both species active and engaged.

Can tank layout prevent aggression?
Yes, strategic placement of caves, plants, and driftwood creates separate territories and hiding spots. This reduces stress, prevents chasing, and allows both species to coexist peacefully.

Is monitoring water chemistry essential?
Absolutely. Both species are sensitive to ammonia, nitrites, nitrates, pH, and temperature. Regular testing and adjustments prevent stress, illness, and behavioral issues, ensuring a healthy, harmonious tank environment.

Do they need enrichment activities?
Yes, hiding spots, caves, driftwood, and foraging opportunities keep them active and reduce boredom. Observing and adjusting enrichment supports natural behaviors and overall well-being for both species.

Can overcrowding affect health and behavior?
Yes, too many fish increase stress, reduce swimming space, and heighten competition. Proper stocking density is critical to maintain activity, reduce aggression, and support long-term health for Bronze Corydoras and loaches.

How do I safely remove sick fish?
Quarantine the sick fish in a separate tank, treat appropriately, and observe for improvement. Early intervention prevents disease from spreading and protects both Bronze Corydoras and loaches in the main tank.

Can loaches disturb Corydoras’ sleeping patterns?
Active loaches may disturb resting Corydoras. Providing shaded areas and adequate hiding spots ensures both species can rest and maintain normal activity cycles without stress.

Do they require special water conditioning?
Yes, using dechlorinated water and maintaining stable pH and hardness prevents stress. Both species are sensitive to sudden changes, so consistent water quality is essential for health and comfort.

How do I manage aggression during feeding?
Provide multiple feeding zones and place food near Corydoras. Monitor interactions and adjust portions to prevent loaches from dominating, ensuring both species eat enough without stress.

Are there seasonal changes in behavior?
Yes, both species may become more active or less active depending on temperature and light changes. Maintaining consistent conditions reduces stress and supports natural behavior throughout the year.

Can tank mates impact their health?
Yes, aggressive or fast-swimming fish can stress both species. Choosing peaceful companions and monitoring interactions ensures a healthy, harmonious environment for Bronze Corydoras and loaches.

Do they need extra care in smaller tanks?
Yes, smaller tanks increase stress and competition. Adequate hiding spots, careful feeding, and regular monitoring are essential to prevent aggression, illness, and reduced activity in confined spaces.

Can loaches affect Corydoras’ schooling behavior?
Excessively active or aggressive loaches may disrupt schooling. Proper tank layout, hiding spots, and balanced group sizes allow Corydoras to maintain natural schooling behavior without interference.

What are the long-term care requirements?
Stable water parameters, adequate space, proper diet, hiding spots, and regular monitoring are essential. Consistency and attention to behavior help both Bronze Corydoras and loaches thrive together for many years.

Is it necessary to provide multiple hiding spots?
Yes, multiple hiding spots reduce stress, prevent dominance issues, and allow both species to display natural behaviors safely. Proper distribution ensures comfort and activity for all tank inhabitants.

**How do I know

Final Thoughts

Keeping Bronze Corydoras and loaches together can be a rewarding experience when the tank is properly set up. Both species are bottom dwellers, but their behavior and needs are slightly different. Bronze Corydoras are peaceful, social fish that thrive in small schools, while loaches are more active and curious, often exploring the substrate and hiding spots. Understanding these differences is important to create an environment where both species can coexist comfortably. Providing a soft substrate is crucial, as Corydoras have sensitive barbels that can easily get damaged on rough gravel. At the same time, loaches enjoy digging and burrowing, so a sandy or fine substrate benefits both species. Adding caves, driftwood, and live plants gives them safe spaces to retreat, reduces stress, and encourages natural behavior. These elements not only serve a functional purpose but also make the tank visually interesting, offering both fish areas to explore and interact without feeling threatened.

Water quality is another key factor in maintaining harmony between these species. Both Bronze Corydoras and loaches are sensitive to sudden changes in pH, temperature, or ammonia levels. Maintaining slightly acidic to neutral water with moderate temperatures ensures that both species remain healthy. Regular water changes and gentle filtration are necessary to keep the environment clean while avoiding strong currents that could stress the fish. Observing the fish daily helps spot early signs of stress, illness, or aggression. If any issues arise, small adjustments in feeding routines, hiding spot placement, or water conditions can make a big difference. Both species are generally hardy when their basic needs are met, but neglecting these aspects can lead to health problems or reduced activity. Proper attention to water parameters, tank maintenance, and consistent care creates a stable environment that supports both species for the long term.

Feeding and social interaction also play a significant role in the success of a mixed tank. Bronze Corydoras are bottom feeders that rely on sinking pellets and small foods, while loaches are often quicker and more competitive during feeding. Providing multiple feeding areas prevents stress and ensures that all fish get enough nutrition. Including occasional live or frozen foods adds variety and encourages natural foraging behaviors. Group sizes are equally important—keeping at least four to six Corydoras and three or more loaches helps satisfy their social instincts and reduces territorial conflicts. Observing interactions during both feeding and general activity allows adjustments to maintain balance. Overall, with thoughtful tank setup, careful attention to water quality, and consideration of feeding and social needs, Bronze Corydoras and loaches can coexist peacefully. They complement each other’s behavior, adding life and movement to the bottom of the tank while creating a dynamic yet harmonious environment. When all these factors are considered, maintaining a community tank with these species is not only manageable but also enjoyable, offering an engaging and healthy aquarium for both fish.