Melos said:
I think a big mistake people make when they set up their pond is putting too many fish in it.
Is there some kind of basic rule for how many koi or other fish you should keep based on gallons, surface area, or total dimensions?
What if you have other animals in your pond as well - like tadpoles, a booming frog population, and even a turtle using it.
There is no really sound formula based on gallons, surface area, or dimensions, although a lot of "experts" offer one. Capacity depends on the total weight of the fish and the cleaning capability of the filter. Weight is not proportional to fish length, and filtering capacity can vary widely within a group of ponds the same size because of different media, designs, and flow rates.
Many dealers have amazing swarms of fish in relatively small tubs because they are turning that water over as many as four times an hour with very effective filtration. On the other hand, a hobbyist pond with barely adequate filtration might only support an average sized fish or two per hundred gallons.
Many people see a dealer display and think that density will work for them.
I have gathered more information on stocking density on my blog
Big Puddle under the heading Choosing Fish. I even venture my own rule of thumb based on weight.
Three rules:
1. You can never have too much filtration. Get as much capacity and pump volume as you can afford. Be sure your pond is cycling before adding valuable fish.
2. You can have too many fish. Stock patiently, working your way up to the right number of fish, monitoring water quality and health. Sometimes playing it by ear is the best science.
3. Do not overfeed. Adjust diet seasonally. Fish that are not getting "enough" dry or live food can always eat algae and plants, but excess food will create noxious waste.
One thing is certain: adult koi require 1000 gallons for swimming room. Raising them in a smaller pond will eventually cause their development and health to wane. You don't need 1000/fish - use the weight scale - but 1000 minimum.
I have no idea what impact tadpoles, frogs, and turtles have on the bioload. I'll leave that to others. You sound like you have a large pond. Good luck with it.
