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.
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
There are many freshwater tropical fish. In fact most of the tropical fish kept by aquarists are freshwater and they can not survive in either cold water or marine (salt) water. In most cases the marine species are much more difficult to keep and much more expensive to set up for.
7....But you should keep an good watch on them.
depends on the species you want to keep... 20 - 50 fishes are good in tank of this capacity
Tropical fish have many colors, so they can blend in with the colorful ocean floor. They have a swim bladder to control their bouyancy. Most tropical fish swim at 640 ft in depth.
there are many caterpillars and fish that are tropical herbivores
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.
Thousands.
There are many species of "Tropical Coral Reef Fish" that are commonly called "Butterfly Fish"