I will get a betta in 2 months and I would really like to train him tricks. To do that I make diy training props and I am not sure about what materials to use because I have heard that some thing are toxic. I am not sure which stuff is bad for my Betta. Is aluminum toxic to bettas?
Here's the thing with hot glue... It's entirely safe, but it's water based so it will dissolve over time. Pure super glue is safe, as is aquarium silicone. If you get Petco to price match their website, the silicone is like $6 and entirely safe. It doesn't take a lot to hold stuff up either.
For hoop training I got those plastic dangly bird toys. You can take them apart or connect them together and teach your Betta to weave in and out of them.