I have two gaint danio fish, one knife fish, one kissing gourami fish, one silertip fish, one algae eater, one betta fish, and one dinosaur bichir in my 20 gallon tank
Oh no..who sold you all of those fish (let me guess, the pet store!).
1. The
Dinosaur Birchir needs to be returned; it can get aggressive and will eat anything it can fit in its mouth as it gets older, including your Gourami. It also needs a minimum of a 55 gal tank (or maybe larger; I've read length of tank is more important, 6 feet long being ideal).
2. The
Giant Danios need more room. They should be in a large tank, at least 40 gals as they can get up to 5" long and they need more swimming room than a 20 gal can provide
3. The
Knife fish (there are many varieties) in general can grow to 19" long. It needs a minimum of a 55 gal tank, depending on size.
4. If the Silvertips are Tetras they are schooling fish and need a number of 6 or more
With the exception of the Betta, Gourami and Silvertips (which the school needs to be filled out) the others are NOT compatible at alll in your aquarium. In some cases they'll probably kill other fish and they get way too big for a 20 gal. The Knife Fish, Birchir, and the Danios need to be returned ASAP. Unfortunately the fish stores sell you anything, but those species are not going to be happy in your tank. Sorry about that.
Forgot to add: what type of algae eater? Since your tank is new there isn't going to be anything for it to eat. I'd highly suggest supplementing with algae wafers and see if it eats it. I'd return this one too until your tank matures.