Hi. I've set up an aquaponics system at home. After my pilot plant using a 40 gal drum and a few grow beds which ran very well, I then up sized to a 5000L system. Things went even better. I only had 10 koi and 3 Red Breasted Tilapia. The Koi came from a shop and the Tilapia from a dam near by.

I then went to a friends farm and loaded approximately 30 kg of fish of varying sizes and brought them home. Within days fish started dying. I put Ich Medicine containing Malachite Green in the tank. Unfortunately I did not read the whole label properly. At the bottom it says not for use on fish that are intended for food. The WWW says Malachite is carcinogenic.

Is there a sure fire way to decontaminate a tank? Does anyone know if the Malachite Green embeds itself in the plastic. So far my course of action is to throw the whole setup away and start again.