Scarlet badis (dario dario) question

So the other day I notice one of my two badis looks sick. The fish was sitting at the surface for a long time. At first I thought it was hunting a snail on the glass. The fish didn't move for a long time. I gently flicked the water to see if responsive, it swam away. The fish swam into the java plant and just laid there. It came back up and I thought it was dying so tried to scoop up and it swam into plants.

I figured it would die overnight. The next day I checked the tank and there it was swimming happily next to the other badis.

Strange. Anyone with experience or research know what could of been the cause?

Here's a bad photo of the 2 side by side.

 

Better photo

 

Poor fish went missing again. Not doing well, had to QT him. I'm suspecting aggression. One of the males is very dominant.

 

Dario dario fish can be very aggressive towards each other. make sure there are numerous hiding places and break up the line of sight in your tank with plants and other decor. Don;t forget that Dario dario fish tend not to be overly active anyway.

 

Yah, found that out. The 2nd male died. These fish are small but aggressive towards their own. He doesn't bother the endlers who swim pretty fast.

While I never saw him bully, I have seen him hunt snails, flare, and show aggressive pose. He was the dominate fish for sure.

I won't be replacing the other dario. I have lost an endler, but never found the body, snails.