Blue Sheatfish

[My Head Hurts]

Ok i keep a pair of blue sheatfish. On the pectorals recently theyve developed a black patch that wasn't there before. Is it to do with sexing or are they just growing? Also, ive had a bit of a nitrate spike so could that be related to itAny info would be useful as these were kind of an impulse buy a year ago. I know basic sizes and feeding etc.

 

[SirMinion]

I had a look at the Blue sheatfish page at Planet catfish, but there's no mention of black spots on the fins.

Do the fish seem unwell in any way?

 

[My Head Hurts]

They're not really spots, more blotches. No the fish seem fine, they are swimming in the filter current and feeding as usual. They seem more pronounced than a few days ago.

 

[Oddball]

New theory for ya mate! The patches appear as the fish approaches sexual maturity. This allows the fish to flick its pectorals to flash the blotches at shoal mates to indicate danger, and in the spawning season it allows them to attract a mate...
Thank the big guy that i held on to a book i was gonna chuck out, stumbled on it this morning mik!