A six inch fish for 100 gallons...............
There are a couple of general rules to determine how many fish your pond can sustain. Unless you have an elaborate filtration system, it's better to have fewer fish than more. Too many fish can quickly overload the pond with high amounts of ammonia that may spike in the hot summer months, causing the loss of all the fish over night.
The total surface area, size and type of filtration system, flow rate, temperature and climate should all be considered when determining the right amount of fish for your pond.
* One 6" fish for every hundred gallons of water OR
* 1" of fish per 10 gallons of water OR
* Total gallons of pond divided by 200 = Total 6" fish in pond