Philpig

Hi all, I have a 400l /125 gallon tank which has some gouramis and rasboras in it. Recently I added 4 Lemon Tetras. They were quite happy and schooling for about a week together, but now all of a sudden they have started staying apart from each other in the tank and when they get near each other, one will chase the other away. 2 seem to be the most dominant, strutting around with all fins very outstretched, while the other 2 seem to be getting chased around most, although I have even seen the ones that usually get chased doing some chasing back. I'm worried that they are going to harass each other until the weaker ones die. Even one morning when it was feeding time they wouldnt stop chasing each other to come up and feed with the rest of the fish!

I've noticed that my 8 harlequin rasboras. who are normally swimming in a school all the time, are now getting quite skittish and swimming individually a lot more.

Is this just the tetras sorting out the pecking order? And should i be worried about it / is there anything I can do?

TFA101

some tetras like your lemons will establish a pecking order, usually the biggest male or female leading the shoal. They will chase and nip at each other and seem to mingle rather than constantly school with each other. The harlequins may feel intimidated by this behavior. I would recommend adding some plants in the tank if you haven't already, to create some hiding places for the fish to retreat to for safety.

I used to own a school of 5 black tetras with that exact same personality. they would always be chasing and nipping at each other, but they would usually get along with the other fish, so to not make them feel threatened

kathyshovel

hi maybe its mating time ?hope it all work out soon

Barbrella

Depending on what else you have in the tank, I would add 5 or 6 more of the lemon tetras. The more there are, the less each one is able to zero in on an individual to harass.

What you're seeing is common behavior for many tetras kept in small numbers, and I just think 4 aren't enough.

platy ben

Sounds like they could be choosing the pecking order like TFA said

Or the males could be the 2 strutting there stuff and the females are getting chased due to mating behaviour

I have 5 harlequins and they also do this about once a month, mine are sorting the pecking order though.