How To Remove A Shiner Brain

I was hoping to have a photo to illustrate. But I don't, so take my word for it, it's surprisingly easy to remove an entire scarlet shiner brain intact. We started this project last Friday, and as a pilot project dissected out three brains. After weighing the entire fish I did the first one, carefully cutting open the dorsal skull with a new scalpel blade under 12X magnification on a dissecting 'scope. The brain is maybe 10 mm long, in the biggest scarlet shiner we could find in our preserved collection. The trick was to remove the brain proper, trimming off various nerves and cutting the spinal cord just where it becomes part of the brain. Each brain is kept in its own numbered Eppendorf tube in 10% phosphate buffered formaldehyde. We still have to go back and weigh those three brains on an analytical balance. An intact large scarlet shiner weighs about 2.3 grams, and I suspect the brain will weigh about a tenth of that. We hope to do this for a series of scarlets and characterize the brain/body size relationship, checking for any sexual differentiation. I have no idea what to expect; no literature seems to exist on the subject for any species of fish, except possibly chondrichthyans. We'll also examine many of these brains with antibody staining to characterize the nucleus olfactoretinalis, a key area in fish brains for learning and sexual differentiation. Once you have the brains, it should be easy(!).

I went out to Limestone Creek with Enrique yesterday, for the sole purpose of netting some YOY scarlet shiners. Enrique turns out to be really good with a pushnet, snagging small scarlets out of the water column. We came home with about 15, ranging in size from about 12 to 20 mm. When I showed them to Amy she started to laugh at the thought of removing their brains, they're so small. I guess if Enrique and Leigh can do that, we should give them Master's degrees on the spot. We'll see.