Dying Platies - Weird Sickness?

[nmerc]

Hi all,

So I've recently had a problem with the fish in my 20g freshwater aquarium. I had 3 blue platies and a redtail dalmation platy. Over the course of a couple of weeks, every single platy got progressively skinnier until one day they just died. Other than the fish getting thinner, everything else about the fish was normal. They behaved normally, ate every day when fed, and did not have any other physical signs of being ill.

The only thing I can think of is the fish acquired some sort of internal parasite? I had a neon blue stiphodon goby that died in the process as well. My other fish are all doing really well; it was just the platies and the goby that were affected.

I haven't acquired any new fish since probably around March. My water parameters are good. Nitrite = 0, and Nitrate and ammonia are very low, though I don't remember exactly what the numbers are at the moment. I do know that they are at safe levels, though. pH is quite high, I think around 8.5? After the platies died, I bought some peat moss pellets to try to lower the pH naturally, thinking that maybe the higher pH had something to do with the deaths.

Can anybody tell me what happened to my platies? What kind of sickness makes them get progressively skinnier without any other symptoms?

 

[absolutangel04]

That can happen with internal parasites. I doubt it has anything to do with your pH. There are also some rather nasty bacterial type things that can cause weight. Unfortunately, it is often tough to say the exact cause of your issue since the symptoms are somewhat generic to multiple issues. Though, the normal behavior is more indicative of parasites IMO.
Do you currently have any other fish showing signs of weight loss?

 

[nmerc]

No, they all look normal so far. I will continue to keep an eye on them, though. I'd like to treat the tank with medicine just to make sure I have no more deaths, but I don't want to mess with adding a bunch of stuff if I don't know what exactly I need to treat.

Just an FYI, the fish I have left include 5 harlequin rasboras, 4 emerald eye rasboras, and a baby bristlenose pleco.

 

[absolutangel04]

Well, there is not really much point in treating it all if you don't know what you are treating for. Meds can have side effects after all, so I am glad to see you would like to use some caution where that is concerned.
Another note, platies and other livebearers tend to get things like this more than other fish. I have seen this sort of platy-wasting before. I would just hold up for now on adding anything else, and then proceed as normal. If you want a medicated food to treat internal parasites, there are some decent ones out there for a reasonable cost. That would be the only preventative option I can think of that isn't too invasive.

 

[nmerc]

Okay, thank you. What brands of medicated food would you recommend?

 

[absolutangel04]

For that, the brands seem to differ heavily by store, so I would go to your lfs and see what they have. I used to like Jungle brand medicated food, but they discontinued it. Look for something with metronidazole in it. I believe New Life Spectrum has a good one if you are in the US. In some other countries, it is hard to find these products though.