but the yoyo loach is a little agressive as they hold their own with the africans - strength in numbers i guess as i call them the 'marauders' - as they travel the tank like a roving gang. and at feeding time (no snails now, so they've gotta eat something else) they don't mess around with getting thei turn at food - sometimes chasing other fish away. so...based on your list of fish, i agree with Cal as the clown loach is known to be a bit more peaceful, and social, with other tankmates. thing is though that clown loaches can get rather big - i've seen them about 6-8 inches at my LFS - given your 30 gal. tank, maybe get just one to see what it can get done on it's own.
best fish for eating snails - The Planted Tank Forum
Clown loaches (Chromobotia macracanthus) are the first fish most hobbyists think of for snail eradication. These fish will eat just about any snail they can find. The drawback to these fish are that they get large. In the wild, they can grow more than a foot long. However, in captivity they rarely grow more than 7 inches long. Still, they are schooling fish, so they need to share a tank with other members of their species to feel comfortable. They are also somewhat picky in their tank mates; they'll get stressed by active, fast-swimming fish.
I have heard dwarf puffers are the best snail eaters, but
What other fish do you have in this tank? Platys tend to eat the snail eggs as long as you don't overfeed your fish, but don't count on this as a solution.
Several types of fish specifically eat snails
Although algae can look good when kept in small quantities, it’s easy to spread out of control if you don’t keep it in check. Introducing algae eaters into your freshwater aquarium, as well as making sure your is up to scratch, can help to prevent your tanks algae production from becoming an eye sore. There are a few different algae eaters to choose from, including snails, shrimps and certain algae-consuming fish. They are cheap, they can help to increase the diversification of wildlife in your tank, and they keep your tank clean, what more could you ask for?darn autocorrect won't let me put in the whole genus species name, I had to put a space in it. They're also called Apple Snails. They're fun to watch, won't eat live plants, which is great if you have any live plants you're interested in keeping alive, and they work as kind of a canary in a coal mine. They're very touchy about water quality, if the water starts going downhill, they retreat into their shells. So any time you see your snail tucked up in its shell, that is your reminder to do a partial water change. Other commenters have mentioned pitted shells. For your expert level aquarist that indicates a carbonate hardness problem. Carbonate hardness is a good thing, it helps stabilize your PH, you want lots of carbonate hardness, but carbonate hardness gets used up by normal stuff, your fish eating and excreting, things decaying, the normal wear and tear in your tank, but if you have a good carbonate hardness, you use up that carbonate hardness instead of having a PH crash. So you really want to do those water changes and make sure you keep up that carbonate hardness with things like crushed shells or limestone or they have water additives, too. It doesn't just keep your snail's shells awesome, it also keeps the PH rock steady, which leads to long term lower stress on your fish, letting them do what they do best.