Abstract

Radiographs are easily performed in sedated fish.¹ However, radiographic detail of internal organs is low due to scant intracoelomic fat.^1,2 Studies on positive contrast gastrointestinal imaging in fish are scarce.^3,4,5,6 The objectives of this study were to describe the gastrointestinal radiographic anatomy and transit times of an endangered species, the spotted wolffish (Anarhichas minor), and to assess the effect of barium on gill integrity in case of regurgitation.

Eight healthy juvenile fish of unknown sex fasted for 72 h and kept at 10°C were sedated by immersion in tricaine methanesulfonate at 95 mg/l. Barium sulfate 105% was gavaged into the stomach at 20 ml/kg under ultrasound guidance. Right lateral and dorsoventral radiographs were obtained prior to and following contrast-medium administration, and at 2, 4, 6, 9, 12, 18, 24, 30, and 48 h afterwards. Additional views were acquired as needed. Gastric emptying and transit times of the proximal and distal intestines were calculated. Measurements of the different digestive sections were also performed on radiographs. Gill biopsies were obtained at t24 h, and 4 months later.

Gastric emptying time was 9–48 h (median 15), proximal intestine transit time was 21–84 h (median 44), distal intestine transit time was 18–72 h (median 33), and total transit time was 48–96 h (median 48). There was no correlation between fish size and digestive transit times. Moderate branchitis was noted on histology at t24 h, but the lesions resolved spontaneously after 4 months. How temperature or depth of sedation affect transit times could be assessed in future studies.

Acknowledgment

The authors wish to thank the Aquarium du Québec and the veterinary technicians who largely contributed to the realization of this project, for their availability as well as their care brought to the subjects of the experiment.

*Presenting author

Literature Cited

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