Saltwater Amphipods & Copepods - 500 Pods - Get 2 for 1 Amphipods can be distinguished from copepods as able to seen at a distance. Amphipods range in size from 5-10mm, where as copepods range from 1-3mm. This listing is for a variety of both. Amphipods and copepods make excellent food for picky eaters like seahorses. Mandarin gobies love th Tanks can be seeded with them by introducing ~500 per 25 gallons or through the use of an upstream f