Backyard Aquaponics
A place to discuss aquaponics

Gday i have a question for everybody,
i was just wondering if there is any pro's or cons to the fish of you ran a system that constantly makes the fish swim?
eg.lap pools , constant currents in FT's


my system at the moment has a constant current and i have seen the SP resting near an air stone. i am thinking the current must be weaker at that point ? ( my ft has a current like a cyclone weaker at the top going in circles and has submersable pump at the bottom taking water out then giving it back eventually on top ) . the water temp was around 17 degrees when i saw them do this , mybe its too cold for them.

Anyways i am really just after the pros and cons of having the FT set up like that .

cheers

I remember seeing a number of photos of trout from members that looked rather fat compared to other trout i've caught. ie deep belly
Do fish need excersise?
Do trout taste fatty from a AP systems?

Lyndon

I think it's more a case of people force feeding their fish..

Different fish species have different "lifestyles". Barramundi like to sit and wait quietly in still water before lunging out at their prey, trout swim quite a lot in fast flowing streams (often)..

is that why the trout like to jump out of tanks then ?

and silver perch ?

I grew up next to a Conservation Department trout farm, and from fingerling, to being stocked in the river, they are never exposed to anything but constant moving water. I always assumed that was an essential part of everyones set up when i read about people raising trout, so I obviously haven't researched your methods a whole lot.

Sure trout will do ok in still water, but lake trout are never as big as river trout in my experience, and healthy trout don't swim downstream...

I saw a doco on tv once where they proved keeping the water moving made fish grow faster and healthier and not so fatty. These were salt water fish but I figure trout would be the same

I would say that more larger trout come from lakes or estuaries than rivers and in many cases the larger fish caught in rivers are ones that move up from the sea on spawning runs. Once they have swum upstream and done their business they turn around and head straight back down and reside wherever the greatest food supply is. The world record trout were all caught from lakes and although the record brown trout in Australia came from a river back in 1887 there have been numerous catches of lake fish only just shy of that mark over the last 100 odd years.

hey john
i would love to see that doco , any idea on what its name was ?

It was called Thalassa a weekly tv series that goes to various areas around the world and shows how people live. These guys were farming ocean fish in a land based setup, pumping sea water thro the tanks. It was in Barbados or somewhere in the West Indies. There biggest problem interesting to us was in getting rid of the fish waste that collected in the bottom of the tanks. By swirling the water the waste collected in the centre where it was tapped off and trucked away. They also by accident found that swirling the water made bigger fish faster, because they had to swim against that current.

It depends on the species of fish. Many salmonids prefer a current to swim against and will be healthier, grow faster, better food conversion ratio, etc. than fish in still water. Others may experience no benefit at all or it may not be good for them.

The only research that I know on the health effects of swimming currents is of trout and salmon. All the studies found positive effects only studies on very small fish with relatively fast currents found adverse effects.

ill def look into that this week john , thanks sounds interesting



so stuart you havent heard of any studies done with silver perch then

LOL!

well i have found the program http://www.sbs.com.au/shows/thalassa/listings/page/ but the actual episode is a bit harder to find . i searched for Barbados and got nothing and i searched for west indies and got something about a guy who messures volcanic activity . does look like a good program though.

What studies were these Stuart?? All the information i have read states that fish put on weight more readily the less energy they use. This theory is why feed manufacturers recommend increasing the size of the pellet as fish grow larger. ie a fish will gain more feed and expend less energy by eating a larger pellet than having to eat many smaller pellets.



The largest trout I have seen in captivity were in ponds with a small flow thru of water which would have caused negligible flow in the pond. What about the Atlantic Salmon industry? Thats based on growout in cages which may experience some current from tides but not what you would call a constant flow.

As far as Silver Perch go I know the fish in my ponds grow much faster than the fish in tanks though I dont expect that this is the cause of any current, more likely due to having access to some extra natural food and lower stocking densities.

Troutman there are three theories as to why salmonids do better.

1.One they use less energy when swimming against a current.
2.They develop better metabolism and consequently growth and health through exercise.
3. Both of the above to a greater or lesser degree.

The first is counter intuitive until you realise that it takes a lot of effort to breath water. When fish are still they pump water through their gills and this takes a considerable amount of effort. For us breathing air is no effort at all but water is heavy and has a much lower concentration of oxygen. Fish find it very easy to point themselves into the current and with very small energy efficient movements maintain their position while ram ventilating their gills.

The second is obvious but the consensus is that three is the most likely. However, since this aspect of fish biology has at this stage merely been noted they have yet to quantify it let alone work out the causal mechanisms. Another interesting note was that in taste tests there was a significant quality difference with exercised fish scoring higher in both taste and texture.