Your 'nominally' 90 litre tank, will actually be holding around 80 litres when you subtract the top inch of the tank that never is filled. You can subtract even more for displacement by gravel and rocks etc.if you have them. Then by applying the basic rules of fish keeping your absolute maximum stocking rate would be 35cm of fish. The basic rules and calculation for keeping any kind of fish are. 2.25cm of fish needs a minimum of 2.25 ltrs of water. :- Every tank needs a permanently running cycled filter. Every tank need to have at least 50% of it water changed evey week. Comply with the above rules and your fish stand a chance of surviving. Fail to comply with them and I can guarantee that your fish will have constant health problems.
Goldfish and such, about 4-6 Tropical Small like cardinals then about 8
depends on the size of the fish, and the length/width of your tank.. the maximum inches of total fish you can get for a 29 (110 liter) tank is usually 20 inches fish. absolute maximum is 29 inches. hope this helps.
72 legs A tropical fish has 72 legs
71 liters is almost 19 gallons and the rule with tropical fish is one inch of fish per a gallon of water at there adult size so it would be different for every fish you got like if the fish adult size is 2 inches that you could have about 10 of that fish in your tank.
Tropical and brackish are not mutually exclusive. Tropical means warm, and brackish means somewhat salty. Many brackish fish ARE tropical, and many tropical fish are brackish. You can keep tropical brackish fish with other tropical brackish fish, if they have the same temperment and will not harm or eat eachother. You can keep some brackish fish with some freshwater tropicals, and similarly you can keep some brackish fish with some marine tropicals. There are no wide open set of principles for brackish fish compatability beyond those that I have just illustrated.
There are many tropical fish on the link i posted that should help if you click on the name you will also get a picture of what the fish looks like. Hope i could help.
it depens on the fish... lol
Thousands.
There are many species of "Tropical Coral Reef Fish" that are commonly called "Butterfly Fish"
There are shark and tropical fish galore, but the Mahi mahi is the game fish of choice.
Crushed
Guppy's are popular tropical aquarium fish and don't have any legs.