Simple detection method for ammonia excreted from fish by using examination kit for ornamental aquarium and its practice in high school

Abstract

Ammonia is toxic metabolite generated via deamination of amino acid. Therefore, ammonia is converted to less toxic products such as urea and uric acid in various land animals and cartilaginous fishes. However, teleost fish and most of aquatic invertebrates excrete ammonia directly into their surrounding water from gill and skin. Nitrification, an oxidation process of ammonia to nitrate catalyzed by nitrifying bacteria, plays a critical role to breed fish in good condition. For evaluation of water quality in ornamental aquarium, various ammonia examination kits are sold on the market. In this experiment, we put some ornamental fishes: gold fish (Carassius auratus auratus), Medaka (Oryzais latipes), angelfish (Pterophyllum scalare var.), and coridoras (Coridoras aeneus) in different numbers into each 250 mL of water followed by measurement of ammonia level by using Tetra-test Ammonium. Ammonia was increased to over 1.5 mg/L when 20 of gold fish or 6 of coridoras were put for 10 min at room temperature. All the students could confirm the obvious elevation of ammonia concentration excreted from the gold fish at a lesson of basic biology. We show here that simple examination kit would be appropriate educational material to realize protein-metabolism.