Quantification of ammonia excretion by selected five varieties of freshwater ornamental fishes

Abstract

Ammonia excretion of five species of freshwater ornamental fishes, platy (Xiphophorus maculatus), swordtail (Xiphophorus helleri), angelfish (Pterophyllum scalare), goldfish (Carassius auratus) and blue gourami (Trichogaster trichopterus). Fishes acclimated for two weeks were incubated for a specific period in closed containers and the ammonia excretion rates were determined. Ammonia was determined using phenol hypochlorite method. Regression analysis of ammonia excretion rate and weight showed that ammonia excretion rate increased with body weight. The regression coefficient of the relationship was 0.4320 in platy, 0.7534 in swordtail, 0.4851 in angelfish, 0.6309 in goldfish and 0.6518 in blue gourami. The weight specific ammonia excretion rate decreased with bodyweight and the slope of the weight specific ammonia excretion rate – weight relationship was - 0.5680 in platy, - 0.2466 in swordtail, - 0.5149 in angelfish, - 0.3691 in goldfish and - 0.3482 in blue gourami. The regression coefficient of total length- weight and standard length- weight relationship are 3.1031 and 3.0565 for platy, 3.1512 and 3.1454 in swordtail, 3.0331 and 2.9656 in angelfish, 2.6191 and 3.0328 in goldfish and 2.9721 and 3.0011 for blue gourami, respectively. The regression coefficients were significantly different from 3 in both the relationships. The weight specific ammonia excretion rate ranged from 0.0032 to 0.0640 g NH3-N/mg/h for platy, 0.0028 to 0.0140 g NH3-N/mg/h for swordtail, 0.0033 to 0.1309 g NH3-N/mg/h for angelfish, 0.0043 to 0.0525 g NH3-N/mg/h for goldfish and 0.0091 to 0.0394 g NH3-N/mg/h for blue gourami. Ammonia excretion rate and weight specific ammonia excretion rate were highest for blue gourami, followed by goldfish, angelfish, swordtail and platy but the weight specific ammonia excretion rate was highest in platy than swordtail for the smaller size group. Quantification of ammonia excretion for standard weight and length facilitates prediction of ammonia build up in a freshwater aquarium