Description of the skeletal anatomy of reared juveniles of Pseudoplatystoma punctifer (Castelnau, 1855) with notes on skeletal anomalies

This study aimed at describing the normal bony skeleton of Pseudoplatystoma punctifer juveniles to use as a reference when assessing the adequacy of nutritional and environmental conditions in experimental rearing during the early developmental stages and to provide a baseline for characterizing skeletal anomalies that might appear in rearing trials with this species. Fertilized eggs and newly hatched P. punctifer larvae were incubated at 27.8 ± 0.4°C in two 60-L tanks (50-L water volume) connected to a clear water recirculating system. At 3 days post fertilization – dpf (2 days post hatching – dph) larvae were reared in three 40-L tanks (30-L water volume; initial n = 2700 larvae per tank; 28.3 ± 0.4°C, pH 6.9 ± 0.2, dissolved oxygen 8.2 ± 0.5 mg L−1, N–NO2 0.04 ± 0.02 mg L−1, N–NH4 0.14 ± 0.05 mg L−1; 0L:24D photoperiod) and fed as follows: non-enriched Artemia spp. nauplii from 4 to 21 dpf (3–20 dph) and a commercial compound diet from 18 dpf onwards. Pseudoplatystoma punctifer juveniles (23.2 ± 5.5 mm standard length, SL, n = 58) were stained with alizarin red and their skeletal structures analysed and identified under stereoscope. Pseudoplatystoma punctifer presents an osseous skeleton typical of catfishes, consisting of a broad and depressed skull containing small eyes, 43–44 vertebrae (44 being the most frequent), a caudal fin complex composed of one epural, five hypurals, one parhypural and two hypurapophyses, dorsal and pectoral fins with spines and anal and adipose fins. The observed occurrence of several skeletal anomalies indicates that the rearing conditions might have been suboptimal.