Another option is to feed your fish more and give your plants more light. In poorer countries where they can't afford pesticides and such, they will simply put more fertilizer, irrigation, etc. This gets the plants to "outgrow" the pest or disease. Good luck, but fighting against nature is like trying to go surfing in a hurricane.

One other wild idea is: try to leave some small opening that is accessible to "bugs" from outside. Eventually, the pests inside will get to such a level that their "scent" smells like an all-you-can-eat buffet to some kind of predator. I pretty much do this outdoors with my lazy gardener approach. You basically get pests once and never get them again (in any significant amount).