The invention discloses a method for culturing loaches. The method includes steps of 1), constructing square culture ponds; 2), disinfecting the culture ponds; 3), breeding bottom water, to be more specific, adding thoroughly decomposed manure and earthworm cast into the culture ponds, inoculating chlorella, cyclotella, cryptophyta and photosynthetic bacteria in the culture ponds and carrying out breeding for 15-20 days; 4), farming lava offspring seeds of the loaches and rotifers in a free-range manner; 5), carrying out raising management. Waterproof walls, waterwheel aerators, blow-down pits, dissolved oxygen detectors and rotifer breeding ponds are arranged in the culture ponds, and the dissolved oxygen detectors are positioned at the bottoms of the culture ponds and are in electric signal connection with electric control switches. The method has the advantages of high culture density, high water self-purification capacity, low sewage discharge, few culture diseases and the like.