Neon tetra turning black

[steph101]

It started on the fin and now half his body is black. 4 of his friends have already died. There is 4 left and i bet he will die next. Not sure if its a parasite? My other fish are fine. Ammonia 0 Nitrite 0 Nitrate 10 and ph 7.6

He seems to be schooling and eating just don't know why he is turning black... and i dont want my betta and cories to become sick

 

[J1Time]

Don't know the reason. But I'd remove him before he spreads it

 

[steph101]

Don't know the reason. But I'd remove him before he spreads it

I think it might be a parasite as I can see that his gills are red and he keeps trying twitching as if he is irritated. Now one of my cories gills are red and he is rubbing on the glass. I am gonna buy a parasite med tomorrow and treat the whole tank. Hope my fishes are ok till tomorrow

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