Yes, kuhli loaches need to be in groups. Kuhli loaches are social fish, and they feel more comfortable when kept in groups of at least three. In fact, kuhli loaches will be afraid to explore the tank and will stay in hiding if they’re alone.
Additionally, you need to make sure to provide your kuhli loaches with enough room to keep them happy and healthy. A single loach needs at least 15 gallons of space to thrive, and each additional kuhli loach requires at least 5 gallons of extra space.
Therefore, you need a 25- or 30-gallon tank to keep a small group of three kuhli loaches.