You could have an Oscar tank containing 1 oscar (can reach over a foot) with a convict cichlid. Convicts grow to about 6 inches in length and are still tough enough if they are getting bullied by the Oscar, but generally small enough as not to be a large threat to the oscar. Silver Dollars are also a good choice to go with an Oscar. Instead of a convict you could have a Firemouth cichlid. I have kept these and they will reach about 6 inches in length, but are still big enough to hold their own against an Oscar. If you want a really agressive fish you could get a Midas cichlid. These extremely agressive fish can reach a foot in length, but you would want to give him the whole tank to himself because he would attack any other fish with him. You could try some smaller cichlids with him, but its hot or miss whether he will accept them. Another agressive fish would be the Jack Dempsey. These guys grow about 8 to 10 inches and can be agressive with other fish in the tank, the same goes with the Green Terror cichlid. Basically cichlids are the way to go with agressive fish, so do some research on any one in particular you find interesting. Good Luck!
Depends on what kind of fish you are hoping to get. That's a big enough tank for most common aquarium fish. Just remember: one inch of full grown fish per gallon of water. As for compatibility check this site. It has a good calculator for that just input the fish you want to get and or check [related links].
There is no 'best fish' to breed in a 75 gallon tank. The best fish will be one that can live in a 75, and you are interested in breeding it.
Jack Dempsey or Tiger Oscar
Well, it depends on their size. From what I've heard, you can put one inch of fish into a tank per gallon, so: 5 one inch fishes of 1 five inch fish etc. It doesn't matter about the fish unless some are aggressive and the others are not.
length and width for a 55 gallon fish tank
you can put a betta in a 5 gallon tank
normal rule for fish in a tank is: For every 1 inch of fish there is 1 gallon of water
You can fit a 5 gallon fish tank on a school going desk.
In that 150 gallon fish tank try to put fish and maintain it
How much gravel for 200 gallon tank
Yes you can.
Betta fish, guppies, tetras.
yea it ate all my other fish. put them in a separate tank with some other puffer fish's roughly the same size. :)
A 1 gallon tank could have one betta fish, but you will need to be diligent about changing the water on a regular basis. The smallest tank that should be used, even for a betta, is a 2.5 gallon tank as it at least gives the fish swimming room.