No, sterlet is the common name of
Acipenser ruthenus, which is a small member of the sturgeon family. If the food is specially for the sterlet, it should be ok, as long as it gets to eat it without the other fish hoovering it up first, but I think it's pretty safe to say the sterlet and the koi should not be in such a small pond anyway. Going on the dimensions you give, the volume comes out at 200 gallons, but as its not rectangular, it will be less, allowing around 40 gallons of space for each full grown goldfish, I would say there should be 5 goldfish in that pond... Doesn't sound a lot when they are small, but they can grow very quickly into impressive specimens when they have room , good diet and clean water.
How many of them are goldfish? and are they standard goldfish or fancy?
Many people don't realise that fish release ammonia through their gills as well as their excretions... Maybe a good point to raise if discussing how many fish should be in there!
Gill
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