Scared Rasboras? Nocturnal???

So I have I 10 gallon tank, all cycled and 76 degrees, with 1 betta and 6 harlequin rasboras, My betta has no problem with the rasboras, occasionally he will flare a tiny bit if they get in his way and they will swim away with no problem, nothing serious. But recently, all my rasboras have been huddled in the corner of the tank with the heater and filter, There is one or two of them that swim around the tank but they goes to the corner sometimes too. Every night I have looked and noticed that once I turn off the light and they all start swimming around and leave the corner. Today I turned off the light just to see if the would leave the corner when I did, and they did! Maybe they come out at night when my betta is resting because they're scared of him? My betta is super friendly towards me, he will swim the front of the tank to see me and swim around until I leave. I've read rasboras aren't nocturnal, but they're acting as it they are!

 

What are your water parameter?
How long have you had the rasboras?

A 10 gallon is typically unsuitable to keep a betta with other fish. Many people recommend a minimum of 20 gallons for a betta to be added to a community tank.

Besides that, how intense is your light? If your fish are new, they still need to acclimate to the tank and bright lights is one of the things they need to get used too along with your presence near the tank.

 

Plants and then some more plants

 

Harlequin Rasboras need shade plants for cover - Cryptocorynes are ideal. They aren't all as nervous as yours in a bare tank, but if you respect their native habitat, they need the security of leaves they can duck under. They even breed on the underside of leaves. They have a close relationship with plants.
One or two "crypts" will spread fast and give you a nicer tank.

Short term - do a 25% water change. Falling water quality will make fish timid.

It's a diurnal species, but it is a fish that likes its sunlight spaced out with lots of shadows.

 

What are your water parameter?
How long have you had the rasboras?

A 10 gallon is typically unsuitable to keep a betta with other fish. Many people recommend a minimum of 20 gallons for a betta to be added to a community tank.

Besides that, how intense is your light? If your fish are new, they still need to acclimate to the tank and bright lights is one of the things they need to get used too along with your presence near the tank.

Not sure what my parameters are, but I got 5 rasboras August 3 (2 died), and 3 more not sure when, probably around the 13th. So I think that the 2 that do swim around are ones that have been there longer. I would think that they would have gotten used to the light by now but idk. Thank you!

 

They don't adjust to us. We have to adjust to them. Their survival instincts run deep, and at their size, they have the right to stay paranoid, if you think about it.