One of my guppies is becoming red, internally? He is normally a pale yellow, but the past two days I have noticed his chest area/gills (not much but I think more than normal) and now his body have become red. He is acting normal, maybe slightly less active but he is never very active anyway.
I have 4 guppies in a 10 gallon tank, he is the only one showing any signs of whatever this is, the others are fine. He doesn't get picked on as far as I see. Two mystery snails in the tank also, seem fine. I have had these guppies for about two months and this just started. I have been having algae growth recently, could cleaning that help him?
I will try to attach the best picture I could get here, his body by his tail did not have ANY red before.
Does anyone recognize this? It almost reminds me of a bruise. How can I help him? Are my other guppies in danger?
Tank information:
10 gal
Ammonia: 0
Nitrite: 0
Nitrate: 5
pH: 6.8
Did a 30% change yesterday.
4 guppies and two mystery snails.