I am trying to remove brains from medium-sized cichlids ranging in size from 16-18cm total length. In previous work with substantially smaller fish (TL: 2-3cm), I was successful in cutting the head off at the operculum, removing the lower jaw, and working my way through to the skull capsule upside down through the upper maxillary bone and surrounding tissues. This technique has not been as successful in these larger fish.
I'd appreciate any recommendations and advice on how to perform this brain extraction! Thanks.
Hello Eugene;
Depending on what you intend to do with the brain later... I've had some success with dissections like this by decalcifying the braincase before I try to get inside. Removing the eyes, lower head and operculae first makes it easier to see what you are doing. I wrecked several before I got it to work.
Good luck! Jim des Lauriers
Not sure if this will work with your size of fish, but this is how I did it with a ~6cm cichlid. Hope it helps!
1. Cut the head off at the operculum.
2. Place the cut surface of the head on the base of the table and make a perpendicular cut that aims to "shave off" the top of the skull, start slightly above the eyes (but probably depends on your species) and try to do the cut it one motion. If you try to do it in many cuts instead of one motion, you risk that parts of the skull that break off will poke the brain's surface. I found it best to use a new blade (i.e. very sharp) that won't bend (see image). The trick here is to not go too deep that you slice off the top of the brain, and not go too shallow because then the brain will still be covered by the skull. Ideally, this should result in the full dorsal part of the brain being visible. (Attached is an image of what was a slightly too deep cut that damaged the left optic tectum, but at least you can see what you are aiming for as far as visible surface).
3. Hold the remaining fish head by placing your thumb in its mouth, and with the index and middle finger on the underside of the bottom jaw.
4. OPTIONAL: With small scissors make a single cut (along midline of face) from the middle of the mouth up to right before where you expect the olfactory bulbs to be. This step helps access breaking off any remaining skull that is covering the rostral telencephalon.
5. Then I preferred to make my way caudal to rostral. Crushing bones around the brain careful to not scrape the brain. Once the spinal cord is freed up, I gently pull it upwards so I can see the underside of the brain and work on severing nerves. At this point, I'd probably be holding the head upside down, cut the optic nerve, then the tips of the olfactory bulbs, and by then the brain should simply fall out.
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