That's probably pushing it a little more than I'd feel comfortable with. 2 weeks with those fish, I wouldn't be all that concerned. 3 weeks just seems like too much. I'd probably have someone come (if possible... ) and feed them twice during your vacation. And if you do, hide all the other food and portion out a normal serving for each feeding.
Glen44 said:You can buy dissolving food blocks that release just the right amount of food each day but the largest you can get is 2 weeks but fish can survive without food for 2 weeks so buy a block and when that's gone they will be fine until you come back. P.S do not try and make up for the food you missed when you come back as your fish will die. Hope my advice helps. pps the auto feeder cost loads of money so food block which are just a few pounds are your best bet.