Grundulis,
The sturgeon are going to be awesome? What is the temperature range you could expect your pond to experience over the season? As in what would be the high for the year in particular as I would guess the pond will freeze over for at least a portion of the winter. Sturgeon are not quite as sensitive to water temperature and dissolved oxygen levels, but they do require fairly cool water and higher DO's, especially when larger. Not as familiar with Russian sturgeon, so I am not sure if they are more or less sensitive.
I can't tell you much about water temperature because it may vary a lot. Last 2 winters were very cold and summers hot but some years before winters were like late autumn. This year spring isn't as warm as is should be... Giving the max. and min. temperature wouldn't tell us much.
The purchase of these sturgeons was inspired by some private pond owners. Somehow their fish survive... Right now, when pond is only with 1/3 of it's possible water amount, sturgeon might feel not comfortable but probably 4-5 m depth would provide good living condition. But, as I said, it's only an experiment
A quick research on them shows they will reach 6' and 250 pounds but are slow growers... From what I understand, sterlets are one of the most tolerant of warmer waters and lower DO's.
What I don't like about sterlets - their max. possible size is tiny compared to sturgeon and that means they probably would grow slower... And I don't think that Russian sturgeon is such a slow grower. Theoretically it may reach 10 kg weight in 4-6 years (in good living conditions). Fishkeeper that sold our these baby sturgeons told that his fish grew from 0,2 to 2 kg during one year (Of course, he fed them). In fact, it can be true as Russian sturgeon is the second biggest fish from sturgeon family (1st place - beluga).
By the way, sturgeon is only gaining popularity right now and only few fishkeepers offer to buy their fry. I've never seen and ad offering sterlets. But I think that it's only a matter of time.
Grundulis,
All species require moving water to reproduce so you can expect them to not multiply in the pond.
I know that...:(
I have heard tench are very good fighters when caught on light tackle
Yeah, it's so. Tench is one very good fish even from other points of view. It tolerates water with low oxygen level, no problems with reproduction, it's very tasty and beautiful fish. But... it grows slow
The one thing that seems to be missing are higher end predatory fish... Is there plans to stock any? Zander, pike, European perch, or another species I am not familiar with? Would the water stay cool enough and oxygenated enough year round for trout?
You are right. Actually there is no need for them now but I will stock some. The only problem is that I can't decide what species should be the best ones.
Pike - works well but grows very fast and eats much. If they manage to spawn eggs then goodbye carps
Zander - would be better but it's very wayward fish. Probably won't live together with carps because very clear water is a must.
Perch - they won't grow big (1 kg fish is considered large; Latvian record perch ~2,1kg) and they spawn like hell.
There are other not so popular fish that can also be used as predators - wels catfish (grows very big and eats much), burbot (doesn't spawn in such ponds), eel (slow grower), chub (don't know where to get it - nobody sells them. The only way is to catch them by myself).
About trout. Here in Latvia only rainbow trout is used as pond fish (golden trout is a subspecies of rainbow trout). There are no problems with getting them but I'm not sure how they would act in summer. Now it's pointless to buy them because of low water amount but after full construction of pond it could be more realistic. But there is another BUT.
I'm worried about different animal predators. We have caught at least 2 otters, 2-3 minks and one heron is seen sometimes. Thanks god, there are no gannets here... Rainbow trouts from upper water are easy catch even for hawks.
