That sounds like a good idea, as long as the tape is non-toxic :) And as long as when it gets wet, it doesn't just fall off. :P I have sometimes used a net to encourage fish toward my cup, but I try never to do it too fast just to keep stress level low... I am just personally overly sensitive about how animals feel, I think... particularly with breathing, cause I don't swim... Had a traumatic event when I was 3, and so I've always been afraid of water/drowning. It's better now that I am an old lady, but... still, the fear is there. So, to me, netting a fish and removing them from their environment where they breathe, and moving them into air, is like me being netted and shoved under water... SO SCARY!!! So I like to keep them immersed at all times... and it works! Just takes a little more patience.
Anyway, sorry for rambling... I'm tired. My brain is still waking up.
I wondered the same about the thai bettas... I bet it's very easy for them to get parasites considering they are outside like that. I mean, I don't know if all Thai breeders method of breeding/rearing fry is the same but... I would assume they are outside.
Update for the morning: Eggie is still floating in her cup (hoorah!) Alive :D... I didn't think she would die, but it's nice to see she is still alive. Her breathing looks slightly better... she has always been a hard breather, so I can't tell if she is "better" or still having trouble. But, anyway, she hates the cup like I said, and in her little head is imaging every way she can possibly escape. I feel bad cause the cup is stressing her out, but, I think removing her from the tank altogether would be more stressful. Her buddy, Goose, (they are in the top ranks of the sorority) was by her cupside this morning as if to encourage her and let her know she was not all alone. :}