Platy changing shape

Question
I have had many platys over a few years, and this is a re-occuring problem I
have. One starts to hang out at the bottom of the tank and eventually the shape
of it's belly changes so that it is flat... or even concave. Not long afterwards it
dies. Do you know why this happens and what I can do to prevent this?

Answer
Hi Stephanie,
I've experienced this before with platies and other livebearers as well.

While I'm not certain of the exact reason, he two most common causes to a condition like this is either due to severe old age or internal parasites. Internal parasites are also distinguished by the fish having stringy white poo but sometimes you never see it. They also will act listless and may not group with the others.

Internal parasites can be a pain to get rid of. But all you can do is try. You'd need to isolate those suspected of internal parasites into a hospital tank. Keep their water very clean with daily 50% water changes, treat with aquarium salt and melafix (gradually add the proper doses to avoid a shock on the fish) and try to get the fish to eat some medicated internal parasite food. This usually comes in gel form. Now keep in mind most fish will not eat this and you'll have to be patient and keep working with them, soaking it in their favorite foods, handfeeding with a toothpick, ect... With persistence they usually eventually get some into their system.

Depending upon the individual circumstance the fish may or may not recover. My experience with a very sickly dwarf gourami and using the treatment I recommend above proved to be quite successful... It took lots of patience and many weeks before the fish was finally cured.

Parasitic diseases can be prevented with good water quality. It is said that many parasites survive in low numbers in your aquarium but the fish naturally are able to fend them off. But if something stresses them and therefore compromises their immune system, the parasites can attack. Just the same as a bacterial disease.

Also new fish can bring parasites into your main aquarium. Quarantining any new individuals for a few weeks is your best bet.

Best of luck and I you can fix your platy problem!
Karen~