More Fun Things To Do With Zebrafish

Yet more fun with zebrafish!  I recently discovered a gene which, when knocked

 down, results in hydrocephalus--the swelling of the brain.  The condition does occur in humans--in fact, I was about to post a photo of a child with a massively swollen cranium to illustrate the phenomenon, but decided it might prove too disturbing for non-medical folk.  The first photo is again a wild-type control--note that the shape of its head is relatively flat.  

Now let's take a peek at this fish I gave hydrocephalus:  the top part of its head is all 

puffed out; furthermore, the head & eyes are noticeably smaller than in the wild-type fish.  

Why do these guys get hydrocephalus?  I'm really not sure, but I have a few ideas and I aim to find out.