Streaked Ventral Fins On Danio

[Lynz781]

My male long-finned zebra danio has streaked "dirty" looking ventral fins that were not like that before. Any ideas whats wrong? His behaviour is normal and everyone else is fine. Well actually my male leopard danio has the same thing but not as obvious. D'you know what it is?

 

[The-Wolf]

any red in the streaks?
what do you mean dirty?
is it dusty like?

 

[Lynz781]

Not red, more a brown colour hence "dirty"

 

[The-Wolf]

The only thing I can think of with, brown streaks in the fins,
is nitrIte poisoning.
I'm sure that is not the case with you Lynz

I Would do a 40-50% water change, in case there is an unknown toxin in the tank.
check all filters to see if they are working at optimum.
I proberbly would treat the tank with melafix, again just to be safe, and observe
the fish for any other symptoms that may or may not appear.

 

[Lynz781]

I did a dip stick test and it detected no nitrites and 10 nitrates (mg/L). It seems the only happy campers in my tank are the cories (won't stop spawning) and thr danios are just being danios. Not having much luck with my mollies. I think they are the wrong fish for my aquarium.