People often ask how big the aquarium should be for one or two Oscars. My advice would be to give your fish the biggest aquarium that you can both house and afford. The rule of thumb and what is uniformly accepted throughout the Oscar fish community is that a single adult Oscar must have an absolute minimum of 55 gallons to itself. This means the fish must have the entire aquarium to itself, no tank mates at all. So if you want to keep even one tank mates as well, you're going to need to start looking for aquariums in excess of 75 gallons. Once you start getting into the realms of more than one Oscar, you're looking at aquariums sizes of 100 gallons and upwards. It shouldn't be difficult to do the calculations, the more Oscars you have the bigger the aquarium. Four Oscars will require an extremely large aquarium of at least 200 gallons. Also, remember that large aquariums need to have filtration to match. Once you start getting into the world of really big fish tanks, you need lots of filtration which doesn't come cheap. You will also need to heat your aquarium as well, a 55-gallon tank can be heated easily with 200 W. However once you start getting over 150 gallons, you're looking at a fair amount of heat that will need to be running 24/7. Remember that all this is going to cost money, lots of money if you are heating large amounts of water.
Aquariums, Fish Tanks, & Stands | PetSmart
Baby angelfish are adorable, and it can be tempting to add a couple to your tank. But these guys grow over a foot tall, and their adult size is much too large for a 10-gallon aquarium. In addition, they are aggressive, new-world cichlids best housed with similar large species, or in species-only tanks. If you want angelfish, consider a or bigger.
155 Items - Find an aquarium and aquarium stand that suits your space
One of the biggest downsides to wall mounted fish tanks is that you need a good wall to mount it on. This means that you need a strong wall and there should preferably be studs underneath for security.
The Georgia Aquarium is a public aquarium in Atlanta, Georgia, USA