Hi there! What I suggest is what I use: 1. a cup. I've got my girls used to me using it - no need for a net. 2. small bowl - works the same, but more space than a small cup. 3. a small container - same as the bowl - just whatever you have on hand
when you use these, cover them - bettas can jump!
I've got my females trained on it,
had Spartan trained to swim into it.... At first they never like it because you can put the cup in fast and it "sucks" them in, but with patience they'll get used to it.