Any ideas why?

Although I am quite happy with the indoor system I have for bringing in winter fish for additional growth, I have an issue with the yellow perch in the smaller of two circular tanks. Although they appear healthy and feed 3 X per day they're swimming around and around the tank at a rapid rate. My concern is they are expending too many calories and this may impede optimum growth. It could also be a stressor.

I know you guys aren't into systems like this but I respect your opinions as you're all very knowledgeable.

Anyway, I have as an experiment I turned off the spray bar that causes the tank water to rotate in a counter clockwise manner to create a centripetal self cleaning action that moves settleable solids to the center drain. Turns out turning it off had no effect on the swimming rate. Next I turned it back on and turned off the center diffuser. Many of the fish stopped swimming and just hung in the water column. Not sure if it was just concern or curiosity that something had suddenly changed, but many did stop swimming around and around. I plan on turning it off for an extended period of time and monitoring the D.O. to see if this is indeed it.

Do you guys think that the turbulence by the diffuser is the or a synergistic effect along with the spray bar, or do you have any other ideas? Have you ever heard of this?


I'm considering moving them into a larger tank that shares the biofilter where there are bluegills. Then using this tank as a centralized tank that I can boil the piss out with a diffuser and potentially turn off the diffuser in the tank that has the fish or turn it down to low rate. I could also insert a foam fractionator into this then fishless tank with no issues with fish.

Edited by az9, 30 December 2011 - 03:51 PM.

Although I am quite happy with the indoor system I have for bringing in winter fish for additional growth, I have an issue with the yellow perch in the smaller of two circular tanks. Although they appear healthy and feed 3 X per day they're swimming around and around the tank at a rapid rate. My concern is they are expending too many calories and this may impede optimum growth. It could also be a stressor.

I know you guys aren't into systems like this but I respect your opinions as you're all very knowledgeable.

Anyway, I have as an experiment I turned off the spray bar that causes the tank water to rotate in a counter clockwise manner to create a centripetal self cleaning action that moves settleable solids to the center drain. Turns out turning it off had no effect on the swimming rate. Next I turned it back on and turned off the center diffuser. Many of the fish stopped swimming and just hung in the water column. Not sure if it was just concern or curiosity that something had suddenly changed, but many did stop swimming around and around. I plan on turning it off for an extended period of time and monitoring the D.O. to see if this is indeed it.

Do you guys think that the turbulence by the diffuser is the or a synergistic effect along with the spray bar, or do you have any other ideas? Have you ever heard of this?


I'm considering moving them into a larger tank that shares the biofilter where there are bluegills. Then using this tank as a centralized tank that I can boil the piss out with a diffuser and potentially turn off the diffuser in the tank that has the fish or turn it down to low rate. I could also insert a foam fractionator into this then fishless tank with no issues with fish.

It could be a synergistic effect causing so much turbity that they were trying to get away from it. Or it may be something as simple as them seeing the bubbles as a structure or a combination of the two. But my guess would be the first one.

I've noticed that yellow perch in nature always seem to be on their way to someplace, and aren't just poking along either. They seem to be a schooling fish always on the move.

I've noticed that yellow perch in nature always seem to be on their way to someplace, and aren't just poking along either. They seem to be a schooling fish always on the move.

I've noticed that too but I had some in a tank last year that didn't swim in a circle around and around the tank. It was a larger tank with an agitator instead of a diffuser and there was no spray bar or center drain.

It could be a synergistic effect causing so much turbity that they were trying to get away from it. Or it may be something as simple as them seeing the bubbles as a structure or a combination of the two. But my guess would be the first one.

Could be but the water is very clear. Not much turbidity.

Could be but the water is very clear. Not much turbidity.

That was my idea too.

Think like a Perch. Clear water = I can be seen => I need to get to deeper, darker, more opaque water. GO, GO, GO!

I have seen one study where baby Walleye won't eat, but will when the water is colored green.

How long have they been doing this? If they were just added to the tank and it's only been a short time, they may just need to get accustomed to the diffuser. You said they are feeding though so they must not be too concerned about it. Is the diffuser near the bottom such that it creates a central column of bubbles all the way to the bottom? I am envisioning a setup like the one in your other thread with the pictures. It would be interesting to see if their reaction would change if the diffuser were moved to the side or suspended closer to the surface. I don't really have any specific reason to suspect that it would, I'm just curious.

I've noticed that yellow perch in nature always seem to be on their way to someplace, and aren't just poking along either. They seem to be a schooling fish always on the move.

I noticed that when ice fishing, you can track a school by watching all the flags on tip ups go up as they pass. Alot of fisherman means alot of a perches path traced.

It does sound like the diffuser is the culprit. I'm thinking that if your spray bar is located toward the top it just may cause enough surface movement to keep the D.O. at an acceptable level without the diffuser. If not, then another spray bar just above the water surface seems like it wuld do the trick. Just for the sake of my own dumb curiosity; were the fish swimming with or against the current of the spray bar?

Please keep us updated on this. It's quite interesting. Thanks.

Steve.

It does sound like the diffuser is the culprit. I'm thinking that if your spray bar is located toward the top it just may cause enough surface movement to keep the D.O. at an acceptable level without the diffuser. If not, then another spray bar just above the water surface seems like it wuld do the trick. Just for the sake of my own dumb curiosity; were the fish swimming with or against the current of the spray bar?

Please keep us updated on this. It's quite interesting. Thanks.

Steve.

I'm not sure how much oxygen the spray bar would add being below the surface of the water. If it's above it doesn't add much to the centrepedal flow from what I've read. There is aeration in the RBC tank with a stone churning things up in there. Water comes back to the perch tank via a siphon tube.

The fish are swimming counterclockwise in the same direction of the flow and the coriolis effect. I turned the spray bar off for a couple of days as an experiment and they are still swimming in that direction. I figured the swimming action of the fish was creating plenty of counter clockwise flow.

I'm not sure how much oxygen the spray bar would add being below the surface of the water. If it's above it doesn't add much to the centrepedal flow from what I've read. There is aeration in the RBC tank with a stone churning things up in there. Water comes back to the perch tank via a siphon tube.

The fish are swimming counterclockwise in the same direction of the flow and the coriolis effect. I turned the spray bar off for a couple of days as an experiment and they are still swimming in that direction. I figured the swimming action of the fish was creating plenty of counter clockwise flow.

Ladies and Gentlemen,

I sent a query to an extension agent for Ohio State and one of the best perch aquaculturists I know. He is also the one I got my original stock from. Anyway here is what he had to say. I feel relieved!

Cecil,

Yes I have as we have nothing but circular tanks. They will constantly swim in a circle, speed dependent on water volume flow rate and direction. In food fish perch culture swimming is good as it builds fillets and not body fat. Also limits nipping at each other. They swim the fastest right after being put in a tank and then often slow down a little bit once they get to it. But always in a circle.

Bill

I have seen this with juvenile bowfin in a circular tank. They are still schooling at that age. There were no spray bars causing any current. They always turned left(counterclockwise) I called them the NASCAR fish. I think they swim in that direction because of the earths rotation rather than current. Kind of like how a toilet flushes opposite in the southern hemisphere.

I have seen this with juvenile bowfin in a circular tank. They are still schooling at that age. There were no spray bars causing any current. They always turned left(counterclockwise) I called them the NASCAR fish. I think they swim in that direction because of the earths rotation rather than current. Kind of like how a toilet flushes opposite in the southern hemisphere.

Yep the coriolis effect.

Thanks all for you excellent input and as usual you some of you were spot on. You guys and gals are awesome!