No, you can’t put a kuhli loach in a 10-gallon tank. Even though kuhli loaches are only 4 inches long and produce a very small bioload, a 10-gallon tank is too small for them to swim around in.
In fact, only very tiny fish can tolerate living in a 10-gallon tank. The only time you should keep a kuhli loach in such a tiny tank is when the fish is a juvenile and you’re preparing a bigger tank for them.
A kuhli loach needs to be kept in a 15-gallon tank or bigger. For every additional kuhli loach, you should add at least 5 gallons of extra space.