Hi, welcome to the forum
To be honest, there are very few algae eating fish suitable for that sized tank. Assuming you mean American gallons (the one most commonly used in fish keeping) that converts to 68 litres.
You could just about fit a shoal of otocinclus, but you would need at least 6 of them, and long term your tank might not be able to grow enough algae for a shoal.
By far the best algae eaters for small tanks are nerite snails. I know some people find just the thoughts of snails to be horrible, but they really are the best. They also have the advantage that they can't breed in fresh water so they don't overrun a tank. Well, they do lay eggs like sesame seeds but they don't hatch.
If you don't want snails, shrimps are the second best option. There are several shrimp species that would be suitable - cherry shrimps in various colours (though red is the hardiest), amano shrimps, ghost/glass/grass shrimp (different names, same species).
However, no algae eating creature will eat all types of algae. The best way to approach an algae problem is to work out why it's there, and remove that issue.
While I'm here, can I point out a couple of potential problems.
White cloud mountain minnows are shoaling fish, you need at least 6 of them.
Clown loaches are also shoaling fish and they grow BIG. Have a look at the photos in that link. You need a tank at least 180 cm (6 feet) x 60 cm (2 feet) for clown loaches. I would rehome this fish before it gets stunted. It really does need to be in a group.
One further comment.
Endlers like hard water, rams like soft water; WCMM like cool water, rams like warmer water. I'm afraid that rams are not really compatible with your current fish.
Do you know if you have hard or soft water? You can usually find that information on your water company's website. This info will help you choose an endler-controlling fish suitable to your water.