Pond Boss Forums GENERAL QUESTIONS Help Sudden death of a lot of fish

I will try to put together a chart here for estimating fish bioload in ornamental ponds. This word processor is not real user friendly when it comes to making tables from data.
1. Divide the pond gallons by 100. This is the fish load limit (measured in 12" fish).
2. In the table find the appropriate size of fish you have in the pond & note the corresponding equivalence #.
3. Multiply the fish load limit (step 1) by the equivalance number (step 2).

This is the approx number of fish of given size you can keep safely in the ornamental pond. So if your pond will hold 30 12" fish, then it will hold 270 6" fish (30x9). It is ALWAYS better to error on the side of too few fish, because the fish you have will hopefully grow if you do not kill them first. Fish that are not growing at a normal rate are probably under some sort of stress.

Fish Lenght Equivalent----Number of fish
(Inches fish Load)---------to one 12" fish
2-------------------------------90
4-------------------------------36
6--------------------------------9
8--------------------------------4
10-------------------------------2
12-------------------------------1
14-16----------------------------0.5
18-20----------------------------0.2

One 12" fish and two 6" fish do not represent the same bioload in a pond. NOTE - expect your pond water to become green right after the biological filter is cleaned. It is not because nitrifying bacteria were washed away, but because the heterotrophic bacteria populations were dislodged. Lots of rapidly reproducing heterotrophic bacteria have been shown in studies to consume lots of phosphorus; more phosphours than the phytoplankton (green water). Phosphorus "feeds" the green water. Ornamental ponds often get real clear when the biofilter becomes clogged. As the biofilters become clogged with heterotrphic bacteria and other organisms the water will tend to clear up as the highly efficient heterotrophic community consumes phosphorus. This is why it is very beneficial to oversize biofilters (2X-3X) so the filters allow for substantial organic clogging by heterotrophs yet still allowing adequate or good filter flow rates.