Sick platy

Question
5 gallon tank might get a bigger tank in a couple of months
4 one inch fish, two pregnant female guppies (Ana & Tory), one emerald cory catfish (Antsy), one male red wagtail platy (swag)
Tank is still cycling(wasn't aware i couldn't get tank and fish on the same day)
I had the guppies for a month in a two gallon with an airstone and undergravel but had to get rid of that tank and decided to get a five gallon
Never really appreciated fish until recently because I have fallen in love with my fish and their personalities even though I've only had the cory and platy for a week and a half, got them when I bought the new tank.
My platy has clamped fins and it looks like fin rot too,looks like the fins are losing color at the tips.Some are spiky then there are chunks missing in other parts and the tail fin is also split in one spot. The fin rot I just noticed yesterday and the clamped fins today but he just started acting funny it was fine before. He is staying close to the top or the bottom, doesn't look like he's gasping for air. The temperature is 76 degrees I have a filter with a bio-wheel and I've been feeding a variety of food, fish flakes, freeze-dried worms, freeze-dried baby brine shrimp. 25% water changes every other day vacuuming gravel once a week. All my other fish look happy and are fine, the platy used to school with my guppies but is staying to himself. What should I do about my platy I am afraid to quarantine since wherever I would be putting him will most likely not have a filter or heater but I don't want any of my other fish to get sick. I am also scared to treat the entire tank. Could it be possible that there is a surplus of bacteria in the water it looks like there are a lot of particles in there even after I do water changes. Should I return him to the petstore, I don't have the receipt but they might take him back. I've read about placing salt in the tank but I heard that corydora's are sensitive to salt. Before this happened he used to race up and down the side of the tank, is this normal? My cory does it sometimes too. HELP!


Answer
Hi Jenny,
  Are the guppies acting aggressively towards the platy?  I ask because the symptoms you describe sound like a fish that is being beaten up, not a fish which is necessarily sick.  Consider putting it in an isolation chamber (even a large plastic tupperware type container or a large glass jar) to see if it improves.

-- Ron
  rcoleman@cichlidresearch.com
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