bluealuefish

I got a new job and slacked on cleaning my tank for 2 weeks.. I finally changed the water today and noticed that two of my neon tetras are sick. They're acting perfectly normal but two of them have discolored patches along the top of their heads and along the red stripe. One is fat (normal sized) while the other one is really skinny. Although there was always a runt in the group, I don't think this one is normally that skinny. It sounds like they have neon tetra disease.

I quarantined both sick fish. Is there anything else I can do? I would not be surprised if the sickness spreads to the other neons.. My poor babies, they were so hardy.. they were my first community fish!

If it is neon tetra disease, will it spread to my other fish? I have 2 cories, 1 oto, 1 rosy red minnow, 1 guppy and 2 baby platies. Thanks. I'll keep you updated.

cerianthus

What were pH, ammonia (NH3), nitrite (NO2), nitrate (NO3) before (if avail) and after water changes?
Ususally NTD, it seems very contagious, where actual infected fish will just hang on top of water , not schooling with the rest of neons but can be suffering from False NTD.
Since in Q/T, how about monitoring to see if they swim or hang on top before deciding on next step? Are they eating still?
Any pics?

Ricardo_NY1

I highly doubt it is NTD. What I believe happened is the following..............

Fish in my opinion, can tolerate and become used to water parameters that are "Dirty", particularly with high Nitrates. You mention you slacked on water changes, so the Nitrates were more than likely on the higher side.

With that said, I suspect you probably executed a water change too quickly, as in not gradual enough. In doing that, you quickly changed the water paramaters. Clean water is important, but so is stability. I think the neons you mentioned were shocked by the sudden drop in Nitrate levels as new water was brought in.

My advice, even when you're a bit behind on maintenance, don't rush a water change. Keep water parameter stability in mind. And when doing water changes, introduce the water as gradually as you can.

As I've mentioned elsewhere, I put an air line regulator between the tube to restrict water flow. Before I thought of using an air line regulator, I used to bend the air line and wrap a rubber band around it to restrict water flow. For my tanks, I'll bring in a 3 litter bottle and let the water trickle into the tank. I'll come back an hour or two later and add another. A 20% water change for me could go for hours. I just basically walk away from it and let the water trickle into the tank. The most gradual level that your time permits, the better.