Fish dont swim

[dmdunne]

Hi there, thanks for reading this and any help offered.

I have recently setup a new 180l tank and added 5 Green Tiger Barbs the barbs seemed happy enough until i then addded 5 Cherry Barbs. Now none of the fish swim when the tank lights are on. They do all come out for food but then return to hiding in the planted areas of the tank. As soon as the lights are turned off the fish will swim around and all seem quite happy and healthy.

Any suggestions for what is causing this/possible solutions?

Thanks again, hope you can help.

[YaYgoldFish]

Have you cycled your tank? And for a possible cause, the tiger barbs might be harassing the cherry barbs.

[dmdunne]

Yeah using fishless cycle and biomature. Water tests show the water as fine but hard, and the Tigers where fine until the Cherrys were introduced.