Right angle corners are used forfull space utilization. Threadfin shad do haul better in round tanks and is why, along with fragility why they are so expensive. A 10" outlet is best with an 8X10 opening better than round. Lids need to allow enough space for a person to get in to the tank to clean and sterilize it properly along with making it as easy as possible to net out fish.

Oxygen is of course important, but a 4" opening for an aggitator is needed also or carbon dioxide will quickly build up and suffocate the fish unless the oxygen flow is VERY turbulent---read wasteful.

When using a good ceramic O2 diffuser like a Point Four, The bubbles are so fine they are dissolved into the water before rising to the surface---any oxygen bubbles reaching the surface are essentially wasted.

Last edited by Rainman; 07/02/10 04:27 PM.