If the water conditions remained perfect; then after one year you would have 25 loaches that were 4" or larger in a 55 gallon aquarium on top of several other bottom dwellers. Talk about a feeder tank. While it "might" work there seems no good reason to do it as this just not even close to enough space. That many loaches should be housed in a 250+ gallon aquarium. If someone wanted to keep loaches in a 55 gallon there are many species that would do well in one. However clown, blue, and tiger loaches are very poor choices.