First mollies...already sick?

[themusician]

Yesterday afternoon I went to PetSmart and bought four sunburst platies and four black mollies to go in my already cycled 20 gallon tank. They are the only fish in there so far. Today I'm noticing that one of my black mollies appears to be gasping (mouth opening and closing a lot and gills moving really fast?), has white spots on its side, and has a silverish/whitish looking thing at the bottom of its eye. My first thought, of course, was ich, but then I came across something called black molly disease which also causes white spots.

How would I tell the difference between ich and black molly disease?

I'm pretty new to fish, but other than the mouth and gill movement my molly doesn't act distressed. It swims around just like the rest of them. I almost wonder if the white marks are natural coloration, from a long ago breeding with a dalmation molly or something. If it weren't for the apparent gasping, I'd be more inclined to wait another day or two to see what happens, but I do think something is wrong. Any ideas?

[themusician]

Actually, I think I may have lied about the molly acting normally. It's hard to tell for sure, but it almost seems like the other three mollies are hanging out together and leaving the other one alone. Or the one is avoiding the other three. I'm not sure which.

[gm72]

Something is wrong, but not at all uncommon to get a sick fish. I would raise the temperature of the tank. You already added salt, I think I remember?

[themusician]

Actually I didn't, because I want to eventually get cories. Should I add the salt and deal with the cories later?

[gem]

If you have mollies.....they need salt. It's not unheard of to keep cories and mollies together, but your black mollies would do quite well with some rift salts, while you cories won't appreciate it at all. Platies aren't too fond of the salt either but can tolrate it to a point. Black mollies can actually be slowly aclimated to full salt.
As for their illness.....I would try adding some aquarium salt (about 1 tsp per gallon diluted in tank water first). Give that a day and se how they look. Raise you tank temp up above 80 f as well. I would go 82-83 with sick mollies. If they start looking like someone sprinkled them with salt I would treat for ich. I use rid ich in combination with raising tank temp and daily 30%water changes with gravel vacuumings. Has been very succesful for me. Make sure you take the charcoal out of your filter if you medicate.
I am not familiar with Black Molly disease. Have always thought that was the Molly wag thing. Not what you are describing. I'm not a fish expert so....not sure.

[gm72]

I would add salt, raise the temp to about 85 degrees. If it is ich, the salt will help kill it and the temperature accelerates the life cycle so they exit the host more quickly. Do frequent small water changes taking care to thoroughly vacuum the gravel, as the parasites will fall into the substrate.

[themusician]

Yeah, I'm thinking I may have goofed by buying these mollies. I've learned several things in the short time since I got them that makes me think they won't be happy in my tank. First of all, the other fish that I wanted to put in the tank aren't compatible because of the salt requirements of the mollies. Second of all, I have CO2 in my tank for my plants which is making my water rather acidic (between 6.0 and 6.8 depending on how long ago I did a water change).

My first thought was to do the best I can with these mollies and then not buy any more if they die. But I hate the thought of letting any creature die when I have the ability to do something about it.

My second thought was to actually get a second tank for the mollies...just a small one because I really don't have the space. But my budget is already shot from this tank...

[gem]

Oh yeah....you definately do not have optimum conditions for mollies. You can usually find a used set up quite cheap. Either that of go buy one of those all in one kits for tropical fish at Walmart. I would get a better heater eventually....but the filter in them is sufficient as long as you are really good about water changes....etc.

[gm72]

Walmart has cheap 10 gallon setups, all you'd need to do is add a heater.

[themusician]

I'm still not sure I have the budget for it, but if I do get another tank, what do you think is the smallest I could get away with for four mollies? Would 6 gallons be okay? I don't know where I would put it, but if it's smaller, it gives me more options.

[gm72]

6 gallons would be fine.