Molly with clamped fins

[Sharkbutter]

My Balloon bellied molly is clamping her fins once again. She does not have any other symptoms besides her usual bit of fungus that flares and clears on it's own. I have a school of neon tetras and a gold fish in my ten gallon. Seems a bit over loaded but they have been fine for months and all levels are reasonably normal and have been consistent.

-No3=10ppm
-No2=0
-Chlorine=0
-Ph=7.5
Temp=78f

The Alkalinity is a little low, but has remained that way for a while. Otherwise they are all healthy and happy (save for one little bout of ich when the school was introduced, but I got it squared away and have had no flare ups).

So does anyone know why a little molly would clamp like that, without any other of the usual symptoms, like lethargy, loss of appetite, etc? What am I missing?

Thanks!

[Venus]

Clamped fins is a sign of toxins (ammonia or nitrite) in the tank; more than likely a spike in the nitrogen cycle is to blame. Every time you add or take a fish away the bio load changes causing the friendly bugs to adjust their colony size.

It's also probable that the mechanics in your filtering system sit at the top of your tank; this makes for weak friendly bug colonies. Goldfish waste is the food source for friendly bugs and goldfish waste sits on the bottom of the tank.

Get a pond or water pump; the mechanics sit on the bottom close to the food source. A water pump will also increase your surface action which will eliminate your bacteria (fungus) problems by increasing oxygen levels. If your tank is enclosed, open it up so the surface receives fresh air.

Perform 20% daily water changes for a few weeks; using water treatment that eliminates chlorine, chloramines, ammonia and nitrite. This will assure your fish are safe.

[Sharkbutter]

Thanks for the idea of different pumps! I never though goldfish waste was processed differently.

Does this still apply if all of my levels are normal?

Also, this fungus, or whatever it is, was a problem before I ever got the goldfish. This might make a difference though they have been coexisting for months now anyway.

I have been treating the molly in a hospital tank with pimafix and she is beginning to perk up a bit. It has only been three days so the cotton has not cleared yet but she stopped clamping. So we will see...

Thanks!

[Venus]

A picture is worth a thousand words. I was suspicious of a spiking cycle when you said; my fish is clamping it's fins 'once again' but after seeing the top loading filter I was pretty sure.

Yes, I saw your test results, but are you using strips or tubes? and if so, perhaps you tested at a time when the parameters were acceptable. Clamped fins is not an immediate response; the fish could have been poisoned days before; with a water change performed in between. See what I'm saying?

Be warned; that taking the fish out of the tank has reduced the amount of friendly bacteria in your tank from the reduced bio load. When you return the fish to the tank again, you're going to get another spike. Keep up with those daily water changes using the water treatment and they'll be safe.

Every time your tank spikes, your fish are being pushed farther into the danger zone.

You can find a pond pump (they come in all sizes) at most lawn and garden centers; even Walmart, or try Big Al's online. They cost only a few dollars; and the benefits are unbelievable. Top loading filters are actually designed for tropical fish that don't experience the nitrogen cycle.


I don't like quarantining fish unless its new and being introduced into an established tank; now that could be risky business. Whatever has affected your fish is in the tank water; if the fish has been with you for a while.

What size tank do you have? I'll recommend an appropriate size pump for you.

One last word of advice; this molly is going to grow and grow and grow. It won't be long before it's eating one neon for dinner and another for desert.