Is your guppy fry lying still at the bottom of the tank, barely moving, while you try to figure out what went wrong?
The most common reason a guppy fry is not moving is poor water conditions, which can lead to stress, lack of oxygen, or illness. Addressing water quality, temperature, and diet is key to helping them recover.
Understanding these simple yet important factors can help you prevent future problems and support your guppy fry’s healthy development in the tank.
Why Your Guppy Fry Might Not Be Moving
When guppy fry stop moving, it can be worrying. One of the first things to check is the water quality. Ammonia, nitrites, or high nitrates can all affect the health of small fry. Poor oxygen levels can also make them slow or motionless. They are sensitive to sudden temperature drops or dirty tanks. Illness, stress from overcrowding, or even poor nutrition may also cause them to appear lifeless. Sometimes, fry stay still to conserve energy or hide from perceived threats. It’s not always something serious, but paying attention early can prevent things from getting worse. A clean, warm tank with enough space and proper food can make a big difference. Testing the water regularly and keeping a stable environment helps reduce risks. If you notice fry not eating, breathing heavily, or sinking to the bottom, it’s a good idea to act fast before the issue becomes harder to fix.
Keeping the tank clean and warm gives guppy fry a better chance to grow and move normally.
Sometimes, fry will stay near the bottom because they’re weak from birth or not getting enough to eat. Others might have internal issues or infections that stop them from swimming. Watching their behavior closely helps you figure out what’s wrong.
7 Simple Solutions to Help Your Guppy Fry
Start by checking the water with a test kit. Ammonia and nitrites should be at zero. Even a small amount can stress young fish.
Once water issues are ruled out, raise the tank temperature slightly if it’s below 78°F. Guppy fry are more active in warmer water, around 78°F to 80°F. Add an air stone or increase surface movement to boost oxygen levels. If your tank is crowded, move some fry to another space so they aren’t competing too much for resources. Feed them crushed flakes or baby brine shrimp several times a day. Weak fry need small, frequent meals. Avoid overfeeding, as leftover food lowers water quality. Consider using a sponge filter to protect the fry while keeping the water clean. If you suspect disease, isolate the fry and try mild treatments like aquarium salt. Keep the lights on a regular schedule, and avoid sudden changes. Sometimes just keeping things calm and steady is all they need to bounce back. Patience and consistency are key.
Common Mistakes That Make Things Worse
Feeding too much too often can cause leftover food to rot and pollute the water. This affects fry health quickly. Skipping regular water changes is another common problem. Poor filtration or using harsh chemicals can also hurt sensitive fry.
Overcrowding the tank is stressful for fry. When there are too many fish, oxygen levels drop, and waste builds up fast. Some people also forget to cycle the tank before adding fry, which means toxins build up and harm the fish. Using water that’s too cold or allowing sudden temperature changes makes fry sluggish. Inconsistent lighting or noise near the tank can scare them, stopping them from swimming or eating. Always check your tank setup and stick to a routine to avoid these simple but harmful mistakes. Small things like skipping filter maintenance or using the wrong food can add up fast.
Not separating aggressive adults from the fry is another mistake. Some adult fish may eat or chase them, causing stress or injury. This can lead to fry staying motionless to hide. Always use a breeding box or separate tank for safety. Also, avoid handling fry or netting them unless absolutely needed, since that can hurt their delicate bodies.
When It Might Be Something More Serious
If water quality, temperature, and food are all correct but the fry still isn’t moving, internal issues may be the cause. Some fry are born with deformities or weak organs. These problems can stop them from swimming or growing properly.
Infections can also be to blame. Bacterial or parasitic illnesses like fin rot or velvet might not be obvious right away but still affect how the fry behave. Look for signs like color changes, clamped fins, or fast breathing. If several fry are showing symptoms, quarantine them and treat the tank. In rare cases, genetic issues from poor breeding practices lead to weak or sickly fry. Always try to get your fish from a trusted source. If one fry stays still but the others seem fine, it might just be a weaker individual. But if more fry start showing the same behavior, take action right away to avoid bigger problems.
How to Tell If Your Fry Is Just Resting
Sometimes guppy fry stay still for short periods, especially after eating. This is normal and gives them time to rest and digest. As long as they move around later and look healthy, it’s usually not something to worry about.
Healthy fry will still react to light or movement. If they dart away when the tank is tapped gently or when food is added, they’re likely just resting. Resting fry also have clear eyes and smooth, steady breathing without signs of stress or damage.
What to Do If Only One Fry Is Affected
If only one fry seems off while the others are active, keep an eye on it separately. Isolate it if needed, and monitor how it eats and moves. Sometimes, individual fry are born weaker or develop issues that others don’t. Offering soft, high-quality food and keeping the water extra clean can help. Don’t medicate unless you see signs of illness. Try not to disturb the fry too much—sometimes, they just need a calm space and time to grow. If the fry continues to decline, it may not be something you can fix, but giving it a fair chance helps.
How Long to Wait Before Worrying
If the fry hasn’t moved or eaten in over 24 hours and shows signs of distress, it’s time to step in. Acting early gives it a better chance to recover.
FAQ
Why is my guppy fry staying at the bottom of the tank?
This usually means something is wrong with water quality, temperature, or oxygen levels. It can also be a sign of stress, weakness, or illness. Sometimes fry stay low to hide or rest, but if they’re not moving at all or breathing heavily, that’s a problem. Make sure the tank is clean, warm (78–80°F), and has gentle filtration with good surface movement. Test for ammonia, nitrites, and nitrates to catch issues early. Even small imbalances can affect fry quickly.
How do I know if my fry is sick or just tired?
Sick fry often show more than just stillness. Look for clamped fins, dull color, bloating, or labored breathing. If they’re refusing food, lying sideways, or not responding to movement, they might be sick. Healthy fry might stay still sometimes, especially after eating or when lights first come on, but they should perk up quickly. Observing the fry for a full day can help you tell the difference. If others in the tank seem fine, it’s more likely an issue with just that fry.
Can one fry be affected while the rest are okay?
Yes, this happens often. Not all fry are equally strong. Some are born smaller, weaker, or with defects that make them less active. If only one is acting strange and the others are swimming normally, it might just be that it’s a weaker individual. You can try separating it into a breeder box with gentle filtration and feed it soft, high-protein food like baby brine shrimp. Sometimes, with extra care, they recover and catch up.
Should I remove fry that aren’t moving?
It depends on the situation. If the fry is showing signs of illness, it’s smart to move it to a separate tank or breeder box to protect the others. Don’t flush or discard fry unless you’re certain it’s no longer alive. Give it some time to recover first. If it’s just staying still but eating and breathing fine, it may not need to be moved. Watch closely and avoid exposing the rest of the tank to stress or illness.
What kind of food helps weak or still fry recover?
Soft, protein-rich food like baby brine shrimp, microworms, or crushed high-quality flakes works best. Feed them small portions 3–4 times a day. Overfeeding causes waste build-up, which makes things worse, so only give what they can eat in a couple of minutes. For fry that aren’t eating, try stimulating them with live food or gently darkening the tank to reduce stress while feeding.
How long does it take for fry to start swimming normally?
Healthy fry usually start swimming within a few hours of birth. If your fry are still and not moving much after the first day, something may be off. They may just need warmer water, more oxygen, or space to feel secure. With the right care, weak fry can start showing normal behavior in 24 to 48 hours.
Is it normal for fry to be inactive at night?
Yes. Guppy fry rest more when the lights are off. Like adult fish, they follow a daily rhythm. If they’re only inactive during the dark period but swim normally when the lights are on, that’s not a concern. Always give them 8–10 hours of darkness to reduce stress and support healthy development.
Can water changes stress guppy fry?
Large or sudden water changes can cause stress. That’s why it’s best to change 10–20% of the water every few days using dechlorinated, temperature-matched water. Avoid strong currents or splashing when refilling. Small, regular changes are safer and help keep ammonia and nitrite levels low, especially in tanks with many fry.
Do guppy fry need a heater and filter?
Yes. Fry are very sensitive to cold water and poor filtration. A small, adjustable heater helps keep the temperature stable around 78–80°F. A sponge filter is perfect for fry tanks because it doesn’t suck them in and keeps the water gently circulated. Without proper heat and clean water, fry can become sick or stop moving.
Final Thoughts
Taking care of guppy fry can feel overwhelming at first, especially when they stop moving or look weak. But in many cases, the problem is something simple like cold water, low oxygen, or poor food. These are things you can fix with a little attention and effort. Guppy fry are sensitive, but they also respond quickly when conditions improve. Watching them closely and making small changes can make a big difference in their health and growth. Even something as small as feeding smaller amounts or adjusting the heater can help them start swimming again.
It’s also important to understand that not all fry will be strong. Some may be born weaker or have hidden health problems. This is normal, and it doesn’t mean you’re doing something wrong. The key is to focus on giving all your fry the best environment possible—clean water, warmth, soft food, and a safe place away from adult fish. If one fry seems off but the rest are active and healthy, just give it a little time and care. You don’t always need to take big steps. Often, simple, steady care is all they need to catch up.
Patience matters when raising guppy fry. You may not see changes right away, but small improvements add up over time. Keep testing your water, feeding carefully, and observing their behavior. Learning what works and what doesn’t will help you care for future fry even better. Guppies are fun and rewarding to raise, and watching the tiny fry grow into healthy fish can be a great experience. Even if a few don’t make it, the effort you put into caring for them helps the rest thrive. Stay consistent, stay calm, and give your fry a safe and stable place to grow.