Here’s one to show the wonder of telediagnosis! Rocky is an Atlantic rock cod, kept as a pet on the research base in South Georgia in the Antarctic! What is wrong with himand do we need to do anything?
The exopht5halmos in this fish is probably caused by gas bubble disease where gas bubbles from supersaturated water give cysts which expand in the retrobulbar space pushing the eye out. Other causes can include gas bubble generation in the vasculature of the choroidal rete which naturally produces oxygen to supply the metabolic needs of the retina. In shallow water this can come out of solution as we have noted in farmed halibut (Williams and Brancker (2004) Intraocular oxygen tensions in normal and diseased eyes of farmed halibut. Veterinary Journal 2004 167:81-6) as shown in this picture. In the former case supersaturation must be prevented as bubbles elsewhere can be damaging, but in the latter situation in an individual animal nothing need be done – Rocky is probably fine as long as trauma is avoided. Interestingly this condition was first noted in cod back in the 1966s (Dehadrai PV (1966)Mechanism of gaseous exophthalmia in the Atlantic cod (Gadhua morua). Journalof the Fisheries Research Board of Canada 23: 909-914)