Hi Brian and bb,

It is a good idea to put plants in the aquarium if it gets some sunlight. Also it is a good idea to use those plants that are the hardiest. Two of the best plants that I use are elodea (small spiral or circular leaves around bunches of stalks) and the vallisnaria species (reed like). I don't know what country you live in mind due. I live in Australia and winters generally do not get too cold.

I am a university gold fish too so I understand that economics is an issue, but you can sometimes find real bargains at markets etc. My sister found a tank for $ 30 and it is 60cm by 30cm by 40cm a real goldfish manstion.

In my tank I have soft elodea on one side and vallisnaria on the other that gives the fish some adventure. I don't care what anybody saids, goldfish can get very bored in plain tanks and it can even make them sick. Two of my goldfish where at babysitting and they almost died they got so sick.

It can be a good idea to put in some interesting rocks and a bubbler. Plus don't forget about food. We get sick of eating the same thing, well guess what goldfish are the same. Your little beauties may like cooked potato, pumpkin, carrot, peas and breadcrumbs. It is also good to feed them bloodworms occasionaly (those they may be expensive). Pebbles are good in the fish tank and if you have plants they can be anchored better to the ground with pebbles and rocks.

I future when fish get sick a 3 percent salt solution is a good idea as others have already suggested and increasing the water temperature approximately two degrees may also help. Sunning the water outside in buckets if possible for at least two - three days gets rid of the chlorine chemicals and then you don't have to put conditioners in your tank (which can weaken fish's immune system and make them very sick).
Best of luck.

Hoover the Goldfish