Black Tinge On Neon Tetras' Fins

[Bangers&Mash]

Hello.

I've woken up today to find that some of my neons, particularly the dominant male, are acting rather aggressive. Many of them, including the dominant male have developed a black tinge to their fins.

This happened around a month ago, then it went away. I've tried looking for the cause online but to no avail.

Can anyone shine a light on this?

Cheers,
Louise.

 

[PrairieSunflower]

I'm not long to keeping neons, but mine all have a sort of... not sure if stripe is the word, but a sort of charcoal (black?) line on their dorsal fins.

 

[Bangers&Mash]

Well it's quite odd as they don't usually sport this colour on their fins. It came on overnight, as had the aggression.

The exact same thing happened before and then it went away. Maybe it's the full moon having a an effect?!

 

[PrairieSunflower]

I don't know, mine move quickly but all seem to have it. Maybe you didn't look closely enough before?

 

[Bangers&Mash]

Hmm.. I've had the dominant male since the summer and have kept a very close eye on him!
It definitely seems to be a rare occurrence, however I'm not sure what's causing it.

Will perform a water change. Am currently in a high-temperature/aquarium salt treatment for ich so maybe that's not helping matters.

 

[Bangers&Mash]

It comes, it goes. Has anyone experienced this before?

 

[BettaGirl_666]

Yes, two out of four of my tetras have a black tinge to their fins, and are very aggressive towards one another. They school at some times, then chase each other away.

 

[FishGuest5123]

What are your water parameters? Could it be ammonia burn? Fins can turn black while healing so it may be healing after nips. Aggression in neons isn’t normal so something is wrong. I suspect water quality.

 

[Byron]

A photo of the black fin would help, this same issue has been raised in another thread too.

As for the aggression, we need more data. How many neons, how long have they been together, what is the tank size (dimensions and volume)? Other fish in this tank? A photo of the tank would help us with the aquascape and fish.