Placing a book/picture/art in front of their tank for awhile ((make sure it’s about the same brightness inside and outside the tank so they can see without the glass making a mirror))

Use a straw to blow bubbles in the water

Show them videos on your phone! (I showed my girl laser pointer videos for cats, and videos of males flaring and she was really into it) (( it might make it easier to see if you turn their light off))

Blow hard on the waters surface to make a little divot/ripples

Get them to jump by getting your finger wet, sticking food to it, then holding it just above the water. This can create a habit of them jumping when you’re near so watch for that

Use a small clear container and offer for them to swim into it. If they do you can lift them out of the tank for a few seconds then gently let them back out, and repeat a few times. Don’t force them into the cup