The confirmation of the number of ornamental fish is actually a calculation of feeding density. It is generally recommended to raise fish with a length of 1 cm in a water surface area with a density of 30 square centimeters. The recommended value refers to the fish with a body length of 1 cm on the water surface of 30 square centimeters, and its oxygen dissolving speed can reach a balance with its oxygen consumption speed. Pig-nosed turtle is a reptile, because it directly breathes the air above the water surface with its lungs, so it can't be counted, but the scavenger is a fish of Crataceae, so it should be counted, because it breathes the dissolved oxygen in the water with its gills.
Another method to calculate the culture density of ornamental fish is to raise fish 1 cm long in one liter of water. The recommended value refers to the speed at which one liter of water dissolves harmful ammonia nitrogen under the action of the filtration system, which can be balanced with the speed at which fish with body length 1 cm produce ammonia nitrogen. So reptiles and fish have to eat and pull, so they all count.