My platy fish has black spots. Is this normal or a health concern?

thanks for reaching out about Bebba. Black spots are often the result of inflammatory or infectious irritations to the skin. Melanin, which is responsible for the black, is part of the immune system in fish. The melanin is mobilized from deep in the skin, to the surface in response to a problem. As a young fish, probably newly acquired, it is worrisome regarding an external parasite. A veterinary visit should be scheduled to perform a skin scrape to identify the parasite, as different parasites require different treatments. Good luck.

Black spots or discoloration can be caused by elevated ammonia levels. Test water chemistry using a home test kit or submit a water sample for testing. Most pet or fish stores will do this for free or for a nominal fee. Ammonia and nitrites should be 0.25 ppm (parts per million) or less, nitrates can be 40ppm or less. Partial water chnages daily should be done to decrease ammonia levels. Use only aged or conditioned water that is temperature matched to prevent further stress or shock. Elevated ammonia levels can be caused by overfeeding, new tank syndrome or overstocking.

This looks like a natural pigment spot, he is colored that way. This is not a disease. I cannot really see the white on his tail, but unless the white spot increases in size or your fish gets more white spots, this may be normal coloring.

If the tank was not properly cycled before she went in, the water qualityu may be affecting her. Check the water parameters first. Temperature should range bewteen 68 F and 78.8 F (20C to 26C). Using a home test kit, ammonia and nitrites should read 0 ppm. Nitrates should be 40 ppm or less. Platys do best in a pH of 7 to 8.3. Adjust parameters as needed and see if it makes a difference in her behavior. Offer a variety of appropriate pelleted and flaked food as well as freeze dried to see if she has a preference. Platys are livebearers with a gestation of around 28 days. She will become noticeably bigger as her date approaches. If she is pregenant and has fry, you will need to separate her or give the fry plenty of cover in the tank. If not, she will eat them. The stress of a new tank and water may also be a factor. Hopefully, with some adjustments and different foods, she will perk up.

It doesn't look like Ich in the images provided. Ich will appear as multiple white dots the size of salt grains on the fish. The fish will "flash" or dart about the tank and rub on objects due to itching. The fish may have an infection or the loss of scales may be due to trauma from other fish. Consider separating the affected fish into a separate tank to recover. If this is not possible, maintain pristine water quality in the main tank and consider a broad spectrum antibiotic. You can find one in the aquarium section of the local Petco. Follow label directions carefully and remove the carbon filter insert during treatment if indicated. You are likely at the maximum number of fish in the tank. As they grow, they shouldn't get bigger than 2 - 2.5 inches, and reach adulthood you may need a larger tank or you may need to separate them.

That is not a good sign. This basically means that your fish is not feeling well. The reason for this is usually either water quality or a temperature problem. You will need to have your water quality checked or check it yourself, and make sure that the thermometer is working and the water temperature is appropriate for the type of fish you have. Check water chemistry using a home test kit or by submitting a water sample for testing. Aim for 0 ppm ammonia and nitrites with a 40ppm or less nitrate level. Perform partial water changes to stabilize chemistry and maintain water quality. Use only aged or conditioned water that is temperature matched to prevent stress or shock. Observe your fish for spots, wounds, blood spots or similar signs and if that happens ask us again, preferably with a good photo of your fish.

Both species are excellent "beginner" fish and quite easy to care for. Your 20 gallon tank is a good size for about 6 to 8 fish of this species. 10 would be close to overcrowding the tank. Once your tank is properly cycled, you can add your fish. They are omnivorous and will readily eat flake, pellets, freeze dried and live foods. Chemistry should be monitored regularly and kept as follows: ammonia 0ppm, nitrites 0ppm, nitrates 20ppm or less, pH about 7, water temperature between 76 F and 78 F. Provide moderate cover (hiding places). These fish are live bearers, so if you have male and female then expect fry (baby fish) at some point. If not separated, fry will likely be eaten by adults.