More pond questions

I live in Orlando, florida and have recently installed a pond on my patio. It is a 25 gal. above the ground barrel pond with 3 anacharis and 2 hardy water lilies. I have a fountain and a filter as I have a few fish in the pond. I also have a snail and a 
plecostamus for cleaning. the filter is rated for 50 gal. My question is how can I stop the goldfish (4 of them) from eating the water lilies? At one time I had 14 lily pads and now I am down to just 8. the lilies are still putting out new growth but they seem to only last about 1-2 weeks before they turn black and die. The snail and pleco take care of the remains. I feed the goldfish about 2 times a day as they are constantly at the water surface. Is there something I can do? Or am I just missing something? The patio is screened in so there is no chance of 
outside invasion.

Pondlady sez:

 I think I am hearing two problems here.
1) Your fish are eating your water lilies
2) Your lilies are turning black and dying.
3) a combination of the two

You have too many fish in that tiny pond. It possibly could support two goldfish. As far as your water lily pads, they only live a couple of weeks and then die off because new pads are coming. You also have one more lily than the pond can support. Give a lily to a friend and keep the one you like best. Feed your lily at least once monthly after May. Oh, and you are feeding your fish too much. They are at the top because they are begging just like your dog does under the dining room table. They are not hungry.