Harlequin Rasboras being aggressive towards Neon Tetras

[Vorka]

Hello all.

We have just added 10 Neon Tetras to our 200l tank which has 4x panda cory and 12x Harlequin Rasboras however the Harelquins seems to be chasing the Neons and attacking them at any chance they get, when the neons first dropped in the tank they were going crazy attacking them.

Can anyone give me some insight as to why it might be happening? All water perimeters are normal etc.

 

[Stiphodon]

If there is a large size difference then the rasboras might be more aggressive.

Saying this it is also quite possible that it is just the rasboras showing what is their territory.

Trying to reduce the aggression would be best to do regular water changes keeping water quality optimal and to feed more to reduce the amount of aggression.

 

[Byron]

Concur with above. Also, is this tank planted, or have sufficient "stuff" to fill the space? Neons are not open water fish, and they do not appreciate overhead lighting, so plants including some floating help, as will chunks of wood or branches if no lower plants. Neons like to remain among these. The rasbora tend to swim mid-water. They can be affected by insufficient "cover" too. Of these two species, I would expect more aggression from the neons than the rasbora, given their inherent traits, but various environmental factors can affect this.