Okay, new poster, so bear with me here.
I recently purchased 6 boesemani ranbowfish from a reputable LFS
(and 2 nerite snails) for my new freshly cycled 60g tank.
They have been in the tank for exactly one week. A few days ago I started noticing that the tops of the heads on a few of them are starting to turn yellowish as well as their pectoral fins. With the coloration of the rainbows, it's hard to tell if it's just the light or if I'm actually seeing something. But I lost a few guppies in my other tank due to something that I think was bacterial (which started with yellow heads and pectoral fins), so I'm a bit paranoid now.
60 gallon (48.25"L x 12.75"D x 24.75"W)
I've done two 10% PWC
since I've gotten them with light vacuuming
and a 25% change this morning once I started to get worried about them.
The only other inhabitants in the tank are the two nerite snails I purchased on the same day. Tank is medium-planted with mostly live plants and a few fake plants.
I usually feed freeze-dried and frozen brine shrimp and bloodworms. They don't seem to like flakes- they spit them out.
I couldn't get a good picture, but I took a short video where I think you can see the discoloration I'm talking about.