Why does my fish float after water changes? Swim bladder disease?

This is a classic sign of swim bladder disorder. Check water quality and chemistry. use a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for 0 ppm ammonia and nitrites with nitrates at 20 ppm or less. pH should hover around 7 and water temp should range between 65 F and 72F. Perform a partial water change is necessary to stabilize chemistry and improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. Pristine water quality is the foundation for recovery and healing. Next, fast her for 3 days. Resume feeding bits of cooked, shelled green peas until she is swimming and defecating normally. You can fast her one day a week in the future and offer green peas to maintain regularity. If symptoms persist, consider a broad spectrum dewormer and a broad spectrum antibiotic. You can find both in the aquarium section at Petco. Follow label directions carefully and remove the carbon filter insert during treatment in indicated.

Confirm proper water temp. Bettas do best between 78 F and 80 F. Low temps may lead to stress and illness. You can also try a small amount of plain aquarium salt (NOT table salt). Salt can aid healing and acts as a general tonic. Use 1/2-1 teaspoon per gallon of water. Driftwood or Indian Almond Leaf can also be used to condition water.

From your description, I think swim bladder disease is possible. There is a really thorough article that I will link below. When you check water parameters, it is important to make sure you also check nitrites and nitrates. Ideally, ammonia and nitrites should be zero and nitrates should be equal to or less than less than 40. If nitrates are zero, it indicates that your tank is not quite nitrogen cycled. If it is higher than 40, then you need to do at least a 50% water change. https://www.thesprucepets.com/swim-bladder-disorder-in-aquarium-fish-1381230

Check water chemistry first. Use a home test kit or submit a water sample for testing. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20 ppm or less. Perform a partial water change to stabilize water chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent further stress or shock. Bettas do best between 78 F and 80 F. By your description, the issue may be swim bladder disease. This can be caused by infection (bacterial or parasites) or constipation. Maintain water quality as described above. Fast the fish for 3 days then resume feeding bits of cooked and shelled green peas. This will help with constipation. If this doesn't help. you can get a broad spectrum antibiotic from the local pet store. Look in the aquarium section. Follow label directions carefully and remove the carbon filter insert during treatment.

Check the water chemistry and quality. You can use a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20ppm or less. Elevated ammonia or nitrite levels can be toxic and could drive the fish to the surface. Water that is too warm may also do the same since it holds less dissolved oxygen. This can happen if water temp is above 82 F. Perform a partial water change, if necessary, to stabilize chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. To treat the swim bladder issue, fast her for 3 days, then feed bits of cooked and shelled green peas until swimming and defecation are normal. Constipation is a common cause of swim bladder disease. You can also consider a broad spectrum dewormer since parasites may also be the cause. Find one in the aquarium section of the local Petco. Follow label directions carefully and remove the carbon filter insert during treatment if indicated.

Check water quality using a home test kit if you have one. If not, bring a water sample to the local pet or fish store. Either may test water for free or for a nominal fee. Confirm 0 ppm (parts per million) ammonia and nitrites. Nitrates should be 40 ppm or less. Partial water changes using aged or conditioned water can be done to improve water quality. Many times poor water quality can lead to stress or infection. The symptoms described may point to swim bladder disease. This can be caused by infection, constipation, stress or parasites. The red rash may indicate infection. Fast your fish for 3 days then offer bits of cooked, shelled green peas until they are swimming and defecating normally. A product such as Maracyn or Kanaplex may treat infection. You can purchase either (or generic antibiotics such as tetracycline amoxicillin or erythromycin) in the aquarium section of the local pet or fish store. Follow label directions carefully and remove the carbon filter insert if indicated during treatment. Make sure water temperature is between 78 F and 80 F, this is the optimal range for bettas.

He may be dealing with some swim bladder issues. The swim bladder is what keeps a fish upright and controls buoyancy. Infection, poor water quality or constipation can affect the swim bladder. Perform a water change. Use aged or conditioned water that is temperature matched to prevent further stress or shock. My choice for conditioners are AmQuel and NovAqua. You can purchase them in most pet stores or fish stores. Bettas are warm water fish and do best between 78 F and 80 F. Anything below 75 F will be stressful. A small tank heater may be necessary to maintain proper temperature. Dissolve 1 teaspoon of plain aquarium salt (NOT table salt) per gallon of water in a cup of tank water and gently pour it in. This will act as a general tonic reducing stress, improving gill function and treating minor infection. Change the water daily to maintain quality and dissolve just enough salt to treat the water being replaced. Fast him for 3 days, then offer small bits of cooked, shelled green peas until defecation and swimming are normal. You can soak the bits in some garlic juice to stimulate his appetite and boost the immune system. Transition to a quality pelleted diet and fast for one day each week to maintain GI health.