Discus ( Symphysodon discus) maintained in aquaria are held in a wide range of water parameters and subjected to many different feeding regimes. In a pilot study, four groups of discus (mean length 12.1 cm, mean weight 57.3 g) were submitted to a radiographic examination to assess the skeletal structure of the vertebral column under defined environmental conditions. Water temperature was 30°C for all groups. Two groups were held at <28.6 mg/L calcium (Ca) and two at 50.0-78.6 mg/L Ca within the ambient water. One of each water quality group was fed a commercial discus diet while the other two groups were kept on a plain beef-heart diet, creating a total of four separate groups. In the case of the beef heart group, dietary Ca content (g/kg) was 0.06 and phosphorous (P) content 2.06, leading to a Ca : P ratio of 0.03, whereas in the commercial diet group a Ca content of 20.1 g/kg and P of 7.36 g/kg resulted in a Ca : P ratio of 2.7. Magnesium (Mg) contents of the beef-heart diet were 0.21 and of the commercial diet 1.69 g/kg. Six fish were submitted to radiography at the beginning of the experiment as a control. After 16 wk of the above diets and environmental conditions, radiographs were taken from all fish (six per group) and evaluated by three independent persons using a scoring system. Alterations were found in all groups. The results of this pilot study give reason to scrutinize rearing and keeping conditions of this fish species.
Animals Animals, Zoo Calciumanalysis Cichlidsanatomy & histology Dietveterinary Female Male Pilot Projects Radiographyveterinary Random Allocation Spinediagnostic imaging Waterchemistry