ill platy?

Question
hi i have a tank with four platy, two coralydis, a gourami, 2 guppy, 5 baby guppy(in net)and six neon tetra i have had them for month's and watch them a lot so i don't think its fighting problems, one of my four platy seem's to have no energy she seems to be breathing quite fast and has lost a lot of weight over the last few days because she does not have the energy to eat, she occasionally swims about a bit but is laying on the bottom at the tank a lot i cant see any problems by looking at her except for the obvious breathing fast and not swimming about can you help please???

Answer
Hi Matthew,
Symptoms like these could point to several diagnoses. And unfortunately it is difficult to diagnose a fish with just a few symptoms to go off of and no knowledge of the past and present environmental conditions (water quality issues), general care, and other such situations that play important factors in a situation like this.

The platy may simply be slowing down from old age. Platies usually live for about 2-3 years or so depending upon genetics and you can't really know just how old your fish already is when you bring them home from the petstore. Some platies are just weak and may not live very long at all compared to the average platy. Internal disorders can also be responsible of course too, like organ deterioration.

Internal parasites can cause a lot of weight loss. The fish often has stringy white or clear poo as well and generally is a listless individual. Not sure if that's what your fish has but internal parasites require a medicated food and can be difficult to cure due to poor appetite in the fish and stubborn parasites.

Garlic extract added to the fish's food is always beneficial in circumstances like this. Garlic is an appetite stimulator as well.

Female platies will especially wear down really quickly if they have produced a lot of babies and/or have been pestered and harassed by male platies excessively. Some livebearer females are very sensitive to water quality when pregnant or had babies in the past and even things like cooler temperatures can prove stressful to them.

An illness is always likely. But hard to determine. Her basic symptoms are breathing fast and listless behavior (not swimming much) without obvious disease symptoms like spots, discolorations, or growths the best thing you can do is investigate into the water quality.

Make sure the ammonia and nitrites are both ZERO and nitrates are under 20. pH is not as important but should remain stable.
Make sure the water temp is around 76-80F and the filter is running at its best (creating good surface movement too)

A 30% water change never hurts in situations like this. Just always make sure to treat the replacement water with a water conditioner and insure the temp is equal to or just a bit warmer than your tank's.

I do hope this helps!
Karen~