I wouldnt say I neglect any fish, but there was this one fish I was forced to adopt by my parents a few years ago, and I didn't like it, it was a bully. So at feeding time, I would always try to give the more 'desirable' pieces of food to the other fish. Didn't work, it ended up chasing the others away and just scoffed the lot.
Then there's my 'dither' silver dollars, once again forced to adopt, I must admit they do add life to the tank, but at feeding time, why cant they take a back seat?! As soon as my tongues go in the tank (as in feeding tonges - to get to bottom dwellers) they just crowd it and nab all the food off it.