Simple method for ultralow temperature preservation of fish sperm

The simple ultralow temperature method of preserving fish sperm includes the following steps: taking fish sperm, diluting with diluent in 1-5 times, balancing in a refrigerator at 4 deg.c for 20-30 min, adding antifreeze agent in certain concentration, packing in 0.5 mm diameter straw, setting on foamed plastic board over liquid inside a foamed plastic case for 20 min, setting the straw into liquid nitrogen inside the case for 5 min, and transferring into liquid nitrogen container for freeze preservation at the temperature of -196 deg.c. The present invention may be used in field operation of preserving fish sperm, and is fast, simple, high in freeze preserving effect and low in cost.