I found yoyo loaches to be the most effective snail eaters, quite literally just a few days after having them in my main tank i noticed piles of empty trumpet snail shells starting to build up. I didn't find clown loaches to be very effective snail eaters, the only snails they seemed to pay interest in were the thin shelled small common pond and ramshorn snails.
The only drawback with yoyo loaches is that to really thrive they do need a sub tropical tank with soft sand and quite strong current from the filter, they do best in groups of 5+. They are very entertaining and attractive loaches though, they are some of my fav fish which i have

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