2 Secure the divider in the tank. Tuck the sides of the frame or the egg crate under the lip of the tank. Aim for a very snug fit. You can further secure the divider with suction cups. Attach suction cups to the frame with fishing line. Use plastic zip ties to attach them to the egg crate.
AreFish Tanks Cruel? An accurately set up, appropriately supplied and all around kept up with aquarium shouldn't be "horrible". The fishes can carry on with a seriously decent existence with simple admittance to food and no hunter pressure. Some fresh water fishes need oceanic plants to stow away.
Coolwater fish do better in temperatures below that, usually between 60° and 75°F (15-24°C), but some of them enjoy water well below 70°F, which is not suitable for any tropical fish. Ultimately the best temperature will depend on the species of fish in the aquarium. Research the fish you are interested in keeping before setting up an wyr7Vgg.