problem with wild freshwater sailfin molly

I have a 10 gallon tank that houses about 6 wild caught sailfin mollies. The dominate male, which is the largest and has the largest, most spectacular dorsal fin has a recurring case of fungus. The male in question is about 2 inches long and all the others are young at only 1" in lenght. I have added sea salt with the hope this would help and quick cure (which is supposed to cure fish lice, fungus, and ich).

Any advice on why only this fish keeps getting recurrent fungus?

By the way I change 25% percent of the water weekly which is treated for chlorine and chlorine.

Thanks for your suggestions in advance.

Wild sailfin mollys tend to not do very well when kept in freshwater, they are actually brackish fish though they do enter freshwater. Sea salt is not used to cure the problems, aquarium salt is used to help fight diseases. Sea salt is used to make salt/brackish water. I beleive aquarium salt is more of a preventative rather than a cure. Once you diagnose the problem I would use a medication dedicated to the problem. Pimafix is a good antifungal treatment. And melafix is a good antibacterial medication. I would slowly start converting your tank to brackish rather than fresh. Many aquarium diseases and funguses do not survive in brackish tanks where the salinity level is constantly changing. In my brack tank when I do my water changes I try to vary the level of salt to stop some diseases and it also makes the fish happier. I do this by sometimes not adding more salt when I do a water change, and maybe a week later I will actually add the salt. Start researching brackish aquariums.
I sure hope this helps a little
maybe someone can help with medication.

Myself, I would add 1 teaspoon of salt (table, kosher, horse, or sea salt) per gallon for keeping mollies normally.

For sick fish, You can go 3 teaspoons per gallon. After the fish are doing better, add 1 teaspoon per gallon of water changed.

Fungus tends to hit places where the fish is injured. Sometimes secondary bacterial infections hit.

3 teaspoons per gallon and cover to reduce fighting between the fish is my advice.

What filtration? How long running?
Underlying H2O quality issues are likely to blame. Maybe he got scuffed up in the net and sub-par H2O is preventing healing.

For the record, sailfins can easily be kept happy in freshwater. They do like lots of room, lots of heat and lots of green stuff to pick at. Give them that and good water quality and they do fine. Hard water may help too.

Wild sailfin mollys tend to not do very well when kept in freshwater

I very much agree with this. You can have a full-time job at a pet shop just pulling dead mollies, goldfish, and fancy swords out of the tanks.

Also, you mention nothing about how long the tank has had fish in it? How much you are feeding? Which can also affect the health of your fish.

Water change regime sounds good!

And melafix is a good antibacterial medication

I know I am going to get flamed for this, but I hate this crap . I think this stuff is a waste of money and has little in the way to show of actual supporting data (data from the company discounted).

Changing water and not overfeeding beat any melafix or snake oils you can add to the tank.

Edited by Gene2308, 23 July 2009 - 06:24 AM.

Im not gonna go off on you. Ive just personally had a lot of luck treating my tank with it.

OK. P. latipinna do require salt, not just that much--a half teaspoon per gallon will suffice.

Joel Trexler did some detailed experiments showing the salinity requirements of this fish. They're available on his home page at http://www.fiu.edu/~...blications.htm.

Equally important, and under rated, is calcium, either from ca+cl (driveway ice melter) or from calcium carbonate. A marine salt mix will provide both. If your water is very soft, you'll need to add more calcium. Hard water you can probably get away without adding any.

Most likely, your mollie picked up a fungal infection from fresh water. A way to knock it out quickly would be to set up a small container of full strength (or greater) sea water as a hospital tank. Sailfins get trapped in high salinity ponds all the time, so the salt won't hurt it. Acclimate your fish to the higher salinity slowly, so you don't stress him out, say, over the course of an afternoon. (You can keep sailfins at salinities suitable for hatching brine shrimp; in fact, keeping newborn fry in a shrimp hatchery for a couple of weeks or so will speed their growth.)

A day or two at the high salinity should knock the fungal infection out without the need for lots of medicines, which tend to be hit or miss anyway.

Good luck.

Kosher salt won't help too much if you have softer water. And rather than fool around with the infection and risk losing the fish, I would bring it up to full strength sea water, at a half cup per gallon for a few days. Move the sick fish to a smaller container, so you don't need to use so much. (It gets expensive.)

Myself, I would add 1 teaspoon of salt (table, kosher, horse, or sea salt) per gallon for keeping mollies normally.

For sick fish, You can go 3 teaspoons per gallon. After the fish are doing better, add 1 teaspoon per gallon of water changed.

Fungus tends to hit places where the fish is injured. Sometimes secondary bacterial infections hit.

3 teaspoons per gallon and cover to reduce fighting between the fish is my advice.

How big are these mollies and what are your water paramaters? 10 gallons seems extremely small for them, especially since they produce a lot of waste...I hope you plan to move them to bigger quarters when they mature.

My trio of sailfins is thriving and breeding in a fully freshwater planted 55 gallon aquarium, but I have no idea if they're wild caught or not. When I first got them, the male had a small patch of white fungus-looking stuff on his side (didn't see it 'til I brought him home), and I debated on whether or not to treat him...but he healed up completely on his own in about a week and it has not re-occured since. Mollies are pretty tough fish.

You can have a full-time job at a pet shop just pulling dead mollies, goldfish, and fancy swords out of the tanks.

True enough, and sad. I remember when live bearers were some of the hardiest. The fish farm hybrid crap today ain't worth a dam. Support shops that sell local bred fish. Much better quality.

Not true at all of pure strain wild sailfin mollies. They are hardy and prolific. people just don't meet their needs.
Mine are something like fifth or sixth generation from a trio taken in full strength sea water. They are in a planted tank and have never had a grain of salt added.

Yes and no. They're pretty unforgiving if the water is not to their liking. They'll die in soft, acid water, but it will take awhile. Likewise, ammonia will kill them pretty fast, especially at high pH's.

Mollies are pretty tough fish.

Jchampagne - that infection might be Flexibacter (aka Columnaris) which often attacks the tail and caudal peduncle. And on livebearers it commonly attacks the head too ("mouth fungus").

Mikez - Have you measured Ca+Mg hardness? I'll bet it's 70 mg/l or more (~4 DGH). Like Bob says the estuarine species of mollies can do OK without salt, but not if Ca & Mg are too low. I dunno, maybe they can tolerate softer water if they get enough Ca & Mg via good diet.

Mine are something like fifth or sixth generation from a trio taken in full strength sea water. They are in a planted tank and have never had a grain of salt added.

How big are these mollies and what are your water paramaters? 10 gallons seems extremely small for them, especially since they produce a lot of waste...I hope you plan to move them to bigger quarters when they mature.

My trio of sailfins is thriving and breeding in a fully freshwater planted 55 gallon aquarium, but I have no idea if they're wild caught or not. When I first got them, the male had a small patch of white fungus-looking stuff on his side (didn't see it 'til I brought him home), and I debated on whether or not to treat him...but he healed up completely on his own in about a week and it has not re-occured since. Mollies are pretty tough fish.

Since all of you have given such great responses to my question, I feel that I owe you all some back ground information that may help to clarify the tank conditions and hopefully expedite a cure.

The 10 gallon tank in question is one of 7 tanks in my garage that are filtered via a manifold with either box or sponge filters (depending on what tank). The sponges are powered by a www.jehmco.com Model# DAPMH15 continuous duty, diaphragm air pump. All of the sponge filters contain and air stone (tank in question is filtered w/ a sponge filter). The box filters do not have air stones, but have gravel and floss. 5 of the tanks have been in operation for about 6 months and the two others only two months or so. The Mollie tank has only been in operation for two months as well (but was seeded with a sponge filter from one of the older tanks). As a matter of fact the tank was purchased the same day I caught the wild mollies (I didn't expect to find them). 1/2 of the water was also from an established tank to help ease the transition and seed the tank with the proper bacteria. I also drip acclimated the mollies into their new tank.

It worked. I haven't lost a single fish.

However, the fungus on the Mollie does bother me and I too suspect water quality. I have read that salt helps fish to cope with ammonia slightly better than with out it, so I added the salt. I also read that Mollies like hard water and minerals that some salt provide and that too spurred me to add the salt. I added salt before any fungal infection was evident. I do plan on keeping all the mollies, but in a bigger tank and/or multiple tanks. Right now I don't have that option.

My present water conditions:

kh (carbonate hardness) 3 dkh
ph 7.8-8.2 (hard to read)
nitrate (20-30ppm fresh reading) and (40ppm salt reading) I do not have a way to measure the salinity. That is why i listed both. There is salt, but how much? I am sure I can purchase a hygrometer if it is deemed necessary.

How do I post pictures small enough to be uploaded? That way I could show and tell.