platys turning white then dying?

I have a 20 gallon tank with 3 ghost catfish, 5 sunset platys, and two mystery snails. I looked in my tank this morning and everyone was fine, active and swimming. I noticed that one of my platys was losing color a bit, but I didnt think much of it. A couple hours later, I came back in to check on them and that same fish was almost completely white and dead. I scooped her out and checked my water parameters. Everything was normal. I came back a few hours later and another platy was completely white and dead. I don't know what could be causing this. My water parameters are:

Ammonia: 0
Nitrite: 0
Nitrate: 20
PH: 7.0
Temperature: 78

 

Could be Columnaris: it spreads quickly, kills quickly (sometimes so fast that symptoms do not have time to show up), and one of the symptoms is a white, often fuzzy but sometimes not, patch or covering on the fish's body or mouth.
Here is an article with more info on it's symptoms, causes, and treatments.

If any of this sounds familiar, you may be in for a long night: some strains move faster than others, but you're dealing with one that moves fast enough that if you see symptoms it is probably too late to save the fish. Treat immediately or risk losing all your fish, and I hope you have some applicable meds on hand because garlic and clean water won't be enough to stop this.

 

If it isn't columnaris, then it is some other fast acting bug. If your water parameters are that good there could be no other reason for the fish to die. Like GemstonePony said, I would medicate the whole tank with a broad spectrum medication. I know that Tetra Lifeguard is a broadspectrum medication that they just introduced onto the market. It is supposed to cover all the major problems fish have. I used it once with very good results. Just a though if you don't have anything else on hand.

 

I actually had some Tetra lifegurad on hand, so I put some into the tank.

 

I've never worked with Tetra Lifeguard so I don't know what all it does, but the only thing to be careful of with many broad-spectrum medications is that if they kill parasites they may also kill snails and catfish.

 

Thank you for that clarification... GemstonePony. I checked and it does say not to use on scaleless fish or invertebrates. The directions say Lifeguard is a broad spectrum non-antibotic agent that treats the clinical signs of disease at their earliest stages in freshwater fish. Added to your aqurium water the powerful oxidizing action of the Haloshield attacks and destroys disease causing microorganisms..... treats infectious ailments such as fungus, ick, red streaks, milky or shedding slime, flukes bacterial disease, mouth and fin rot, clamped or torn fins and unlcers. May be used as a preventetive when adding new fish.

Active ingredient: 1 chloro 2.2, 5.5 tetramethl-4-imidazolidinone

Hope that helps clarify.

 

In that case, I would in the very least get the snails out of there and only use a half-dose. And that's only until you can get a safer anti-biotic med. since I can't guarantee the Lifeguard will work at a 1/2 dose, but it may be better than nothing. I've killed neon tetras and gouramis with stuff marked "may be harmful to scaleless species and inverts," and catfish are considered scaleless and snails are inverts.