Fish question.

[Reefind]

Is there any fish that eats algae and can be kept in 20 gallon tank?

[iamwrasseman]

algae blenny ,small tang but he would out grow your tank quickly but you may be able to work a deal with your lfs to trade him in for another small one . its not the best setting for a tang but it is an option .
you could set up a critter tank and have crabs ,snails and a algae blenny as that would be a better option . there are many different and very awesome looking crabs ,lobsters and snails and even some conks that make great looking inhabitants . my wife has a critter tank and everyone that comes over looks at that tank more than mine that have thousands of dollars in livestock in it .
you have many options so take your time and plan it out !
good luck

[Reefind]

Thanks for the quick reply, is it safe to keep algae blenny with yellow clown gobies?
How many blenny can I keep?
At this moment I have some crabs and snails, I also like critters tanks, I have freshwater tank with many shrimp,crayfish, snails...but I don't know much about saltwater.

[iamwrasseman]

depending on the aggressiveness of the blenny as some defend their territories to smaller fish but will leave "critters" alone .there are so many little things that you can purchase that make a very interesting tank . i am very lucky as my favorite lfs gets in all sorts of weird stuff and i get a couple of each . my wife's tank is full of them and its awesome .

[kingfisher62]

You could by a seahare , but after your algae is gone you would want to pass it on to another reefer because it will starve without algae.