Neon Tetra Seems To Be Sick

[squidneh]

I have a neon acting and looking strangely. Any help would be appreciated. No other fish seem affected by whatever is wrong with him.
 
Tank size: 75g
pH: 7.8
ammonia: 0
nitrite:0
nitrate: 10ppm
tank temp: 78

Fish Symptoms (include full description including lesion, color, location, fish behavior):
-dull coloration: looks like they all do at night time, not showing much color at all
-weakness: seems to struggle in the current of the filter, although it isn't very strong and the others do fine in it. Even the ghost shrimp swim around no problem
-doesn't school with the others
-I haven't witnesses him eat at the surface with the others, though he may get some flakes that sink. I don't really have a way of telling
Volume and Frequency of water changes: 35% weekly 

Tank inhabitants: - 1 rainbow shark, he does not even glance at the tetras. 1 CAE, peaceful. 1 female opaline gourami, also peaceful. 8 other neons, and  4 bronze corys

Recent additions to your tank (living or decoration): The last additions were 5 additional neon tetras about a month and a half ago. I have no way of knowing whether this one is a new one or one of the originals, which i got nearly a year ago

Exposure to chemicals :I dosed with pimafix and an API general treatment upon noticing the sick neon, usually no chemicals otherwise

 

[Byron]

First suggestion is to stop adding the treatments.  They will probably be of no benefit to the sick fish, but could make things worse.  When fish are not "healthy" they are weakened, and any substance added to the water will add stress, which weakens them even more, even when it is the correct medication.  So only when it is a certainty that this or that medication/treatment will benefit should it be used.  I don't know what is in the API "general" stuff but such products rarely if ever benefit anything, in my experience.
 
As for the tetra, this may just be the fish.  These days, neon tetra seem to be in very bad shape generally.  Some have suggested this is the result of decades of commercial in-breeding, and this is probably true.  I have also noted lately (last couple of years) that commercially-raised species tend to have more health issues than before, and my wild-caught fish never see to bring these with them.  These fish may be exposed to issues in the hatchery or it may be genetic.
 
When I see a single fish behaving as you describe, I tend to either leave it alone or, if it worsens, net it out and euthanize it.  They never recover, and provided whatever it is does not spread, I don't worry.
 
Byron.

 

[squidneh]

I would just like to add for the sake of others who may stumble upon this in the future, my neon made a turn for the better after dosing with pimafix and the api general treatment.  The fish is now schooling with the others and looks and is acting normally. It seems to cause and effect to be coincidence.
 
I'm not attempting to advocate medicating without knowing what is going on, but in the case of neons where as Byron pointed out, they often are just weak from bad breeding, it may be worth a shot as a last ditch effort.