Strange Rainbow Behaviour

[dayzofspeed]

while i was watching my fish this evening one of my male dwarf neon rainbows began some strange behaviour that i've never seen before,he began to single out and chase 1 particular head & taillight tetra, he would chase the tetra at high speed and get in front facing the tetra, and angle his head downwards slightly then with a sort of quivering motion shook his head from side to side very rapidly, he did this for a couple of minutes and although curious i thought nothing of it. this then stopped for about 10 minutes when he started over again doing exactly the same thing, it's also worth mentioning that his colour also intensified a bit but not excesively but something that did strike me as strange (because i've never read of it happening)whilst he is posturing at the tetra he develops an orangish stripe which runs along his back from his nose to his dorsal fin, is this just the behaviour of a confused/frustrated male fish with a crush,there are no females of his species at present in my tank, or could there be another explanation i.e madfish disease lol, any suggestions !!!!

 

[drobbyb]

That particular behavior is aggression since it is a different species. If he was doing that to a female, it would be courting/breeding behavior. The stripe you see all rainbows have and they use it to show dominance and to show how colorful they are to potential mates.

 

[dayzofspeed]

could this aggression be due to the fact that at the moment there are only the two male rainbows as i am waiting on my lfs getting a new batch in, hopefully when they arrive i can get 3 females

 

[drobbyb]

Rainbows are kind of liek tetras, they need at least 6 members in their shoal to spread the aggression around, otherwise they can get kinda mean.