yellow lab sick need help

[dornblaser1]

i have 10 african cichlids in my 75 gallon tank i havent added any fish since about a month ago and about a week or so ago one of my yellow labs started turning a very dark and dull grey/blackish color. It doesnt eat and pretty much always rests against something on the bottom of the tank for hours on end. the fish doesnt swim right either and has labored breathing. any help of what i can do to save this fish is greatly appreciated
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[Kvnr14]

We need more information, like what are your water parameters and what kind of filtration?

 

[TheGrza]

How long has the tank been setup? What are the other fish in the tank?

 

[dornblaser1]

ph 7.8
ammonia 0.25ppm
nitrite 0ppm
nitrate 10-20ppm
using api fresh water master kit

temp is at 80 degrees
i am using an aquatop cf500uv canister filter bottom media tray coarse sponge and filter floss, middle 2 media trays fine filter cloth then ceramic rings, and top fine pad w carbon, 2 power heads 6 hour light cycle w a 4 bulb t5 ho fixture

tank has been up for about 2 months and 1 female acei, 1 poss. (Haplochromis sp. "#44" thickskin), 4 yellow labs, 3 ob red zebras, and one cory cat which needs a new home

 

[isiah1820]

Could be from fighting, noticed it fleeing from other fish?

 

[dornblaser1]

not really he doesnt eat at all and just lingers in different areas always hiding

 

[isiah1820]

Was asking b/c I have a female lab who kinda acts the same but she eats but gets harassed by my male zebras and ob

 

[dornblaser1]

yeah you can see its turning a greyish black color on its sides and its not bright like my other 3 labs