First off, I'd like to say that I am SO glad I found this forum. I had no idea just how woefully ill-informed I had been about what sort of environment a betta needs.
Eager to correct our errors, we recently purchased
this aquarium for our lovely crowntail, Alucard. We haven't put him in it yet, but we've got it all set up and it looks great. There's just one thing that worries me...
This aquarium has a tube in the center for the air filter, and it came with a small, plastic ring that sits atop the tube to keep your fish from swimming down into the tube. The problem is, I'm not sure the spaces are small enough to actually keep Al out if he got curious.
If I keep the water level just above the top of the tube - or perhaps even below it - would this be all right? I don't see any reason why it wouldn't, but I'm new to aquarium keeping and I'd prefer to err on the side of caution and ask the experts.

Thanks, in advance!