Sturgeon at Fish Story

[thebiggerthebetter]

We got unbelievably lucky by getting two beluga Huso huso and two sevruga Acipenser stellatus.

Yet this is but an experiment to see if we could keep water oxygenated enough over summer to keep the sturgeon alive. To keep the water temp down we have installed two high speed fans over the water surface and the waterfall and a 500W water chiller, both of which seem to keep the water temp lower by about 5 F than it'd normally be, that is 79-81 F versus normal 84-86 F for this time of year.

The sevrugas came in emaciated and in a couple of months we lost one already. I don't think I have ever seen a fish that would lack the instinct that tells it to go where the feed is offered and laying on the bottom but such are our two sevrugas, they appear clueless as to where the feed is offered spatially, when it is offered, where it is laying on the bottom. I fail to deliver enough feed to them because their tank mates don't wait around. Their gill plates are underdeveloped and their pectoral fins suffer from a bad curl.

 

[sikoko]

Good rescue but I always enjoy your threads

 

[thebiggerthebetter]

As expected, the other sevruga has followed the plight of the first one. It's frustrating beyond words when you offer a hungry, emaciated fish feed and it swims away in the opposite direction.




One of the belugas is the same way, not recognizing when and where the feed is being offered and slowly wasting away, while the other is the only one of the original 4 sturgeon I am happy about as it feeds well and grows well.

The two beluga footage in the end of theis video (the rest is not related to sturgeon):

 

[thebiggerthebetter]

The remaining two belugas have been doing well. One had been feeding quite well even in the hot season when the water was 80-82F (aided with fans and a chiller), while the other only started to feed much better when the exhibit water had started to cool in Nov-Dec. As a result, one is 2x the girth of the other. Lengthwise, they probably added around 6" since Apr 2020.

They like both pellets and fish but like the most a thawed and fortified whole herring, currently about 6"-8" long.

Hard to take good pics of them in the large dark pond with glare off the front glass facing outdoors, so some really poor ones:

 

[thebiggerthebetter]

The belugas have been doing well. The supposed female (3.5 ft, far rounder) always feeds much better, especially when it comes to whole herring than the supposed male (3 ft). The female actively searches out the herring while the male half the time cannot or wouldn't try to swallow the herring when it stumbles upon it during feedings.

The male fed better in the winter time (water temp 68-72 F) then now in the summer (78-82 F), so this may have to do with the water temp.

 

[Chub_by]

Looking good, mate. It's interesting that you observed they prefer herring, many keepers report that they only develop a taste for fish once they are well over a metre and will prefer pellets or crustaceans like shrimp beforehand. I am curious to see whether they will start to go after your other fish (albeit I hope for you they won't ?)

 

[thebiggerthebetter]

... and will prefer pellets or crustaceans like shrimp beforehand...

This is similar to how my supposed, smaller male feeds, preferring pellets (I don't offer shrimp), but can't fill up on pellets, so he is forced to take herring.

 

[thebiggerthebetter]

Just a side note for the record that we have given Siberian sturgeon, Acipenser baeri, a try 5-6 years ago. Got 5 from a local FL vendor, who imports fertilized eggs and then hatches and raises the fish. They have done well for half a year feeding vigorously, but didn't survive their first summer, dying off one by one over a course of a few months. Didn't look like an illness at all.

I believe what did ours in was stress from

[1] the low hardness and TDS (low KH, hence unstable pH) and/or

[2] high summer temperatures, as the water in our main pavilion exhibits gets up to 85-88F.

 

[Chub_by]

Just a side note for the record that we have given Siberian sturgeon, Acipenser baeri, a try 5-6 years ago. Got 5 from a local FL vendor, who imports fertilized eggs and then hatches and raises the fish. They have done well for half a year feeding vigorously, but didn't survive their first summer, dying off one by one over a course of a few months. Didn't look like an illness at all.

I believe what did ours in was stress from

[1] the low hardness and TDS (low KH, hence unstable pH) and/or

[2] high summer temperatures, as the water in our main pavilion exhibits gets up to 85-88F.

I will go out on a limb here and say it was stress from the high temperatures (and possibly from consequential low dissolved O2)
Remember that while all sturgeon prefer cooler waters than you have in a Florida summer, Belugas as you know occur in the tributaries of the black and caspian sea, while every single river in the siberian's range empties into the Arctic Ocean and is considerably colder still. Siberian sturgeon are often stocked in ornamental ponds in Germany and struggle in warmer summers even here.

 

[thebiggerthebetter]

Eleven nightly meals served. Sturgeon were of secondary focus. Some great footage was caught of one beluga violently repositioning an 8" herring inside the mouth for swallowing. This is typical for them, I suppose when they inhale the herring tail first and want to reposition to head first.