what is the cheapest coral for a 20 gal to be compatible with...?

Question

clowns ?

Answer 1

If you mean anemones, the one that you should get is the Bubble Tip Anemone, as they are one of the hardiest species that you will be able to keep alive in an aquarium. Conversely, Sebae anemones are hard to keep alive even though they are quite beautiful species.

If you actually meant corals, there are a variety of corals that you can keep. Just forget about hard corals, a 20G simply isn't big enough.

1. Star polyps - http://www.fishstart.com/fish-identification/StarPolyp-1.html
2. Finger Leather - http://www.fishstart.com/fish-identification/FingerLeatherCoralCladiella-1.html
3. Zooanthids - http://www.fishstart.com/fish-identification/ZoanthusButtonPolyp-3.html
4. Mushrooms - http://www.fishstart.com/fish-identification/ActinodiscusMushroomCorals-7.html
5. Ricordia - http://www.fishstart.com/fish-identification/RicordeaMushroomCoral-6.html

Another thing to consider is lighting. If you can afford a few hundred dollars I'd go with metal halides as it is closest thing you can get to the Sun. But these corals don't require intense lighting, so you'd get away with power compacts and it will still look quite beautiful.

Answer 2

I think you mean anemones, don't you? That's what the clowns live in and around.

You are asking for a lot of trouble trying to keep anemones, coral and clowns in a 20 gallon tank. Even experienced salt water aquarists don't try to keep anemones in anything less than a 50 gallon tank. The reason being salt water has to be perfect for anemones to even survive, let alone thrive.

If you have no experience with marine tanks, do a lot of research before you start. A basic starter set up for salt water before you start buying fish will run you about $500.

Good luck.