Gammarus

[Khmer Aquaponics]

Hello! Has anyone got this guy in the system?  This little guy has done a great job at Friendly Aquaponics ,and now I doubt how this little guy exists in their system. 

[Jon Parr]

Awesome pics. Thanks

[Chris Smith]

Keith, are you providing food for your gammarus other than your experiment? If any animal is hungry enough it will eat things that are outside their regular diet just to survive. I have gammarus but they prefer to live in the sludge at the bottoms of my troughs and where dead organic mater accumulates. If they were starved them I am sure they would start eating roots in my system, but they have plenty of dead organics to eat. The sludge in my troughs is primarily from dead bacteria. The gammarus eat the sludge and release the nutrients back into the system.

[Keith Rowan]

in my culture tanks, i feed them cuttings from the gb's, but not every day.. i've completely ignored the tanks for a week, and they were getting taken over by water lettuce and duckweed (duckweed usually wins, unless there are tilapia around!)

even in my other tanks (all have some scuds) they spend time on roots, but i've only observed them eating dead material

i started using a 2 liter wide mouth juice bottle to "skim" the surface of the tanks, and harvest both duckweed and scuds at the same time - this can be fed to the pool with tilapia and perch, or the ibc with just tilapia fry

but it's much easier to put a big ol' leaf in the culture tanks early in the day, and just pull it out and shake it in a  bucket to gather hundreds

 

[Khmer Aquaponics]

Thank so much for the experiment and the pictures. However, I just wonder how well the scuds performed in getting rid off the sludge. I agree with Chris that those scuds that they would eat up all the root if they are starved. However that would be fine if they eat only dead material.  In Cambodia,  I see no clue to find them in the wild. 

Keith Rowan said:

in my culture tanks, i feed them cuttings from the gb's, but not every day.. i've completely ignored the tanks for a week, and they were getting taken over by water lettuce and duckweed (duckweed usually wins, unless there are tilapia around!)

even in my other tanks (all have some scuds) they spend time on roots, but i've only observed them eating dead material

i started using a 2 liter wide mouth juice bottle to "skim" the surface of the tanks, and harvest both duckweed and scuds at the same time - this can be fed to the pool with tilapia and perch, or the ibc with just tilapia fry

but it's much easier to put a big ol' leaf in the culture tanks early in the day, and just pull it out and shake it in a  bucket to gather hundreds

 

[Jon Parr]

Scuds can take care of all solids, I believe. I shot this video just to show my family, but it will give some testimony to the use of scuds.


http://www.youtube.com/watch?v=NRkxMvbLAxg&feature=youtube_gdat...

I found mine in a seasonal local creek that was drying up, and had isolated pools of filimentous algae. Scuds were thick, caught many hundreds in a few minutes with a spaghetti colander.

[Khmer Aquaponics]

Thanks Jon for the information and the link. I really wanna see them directly with my two eyes. 

Jon Parr said:

Scuds can take care of all solids, I believe. I shot this video just to show my family, but it will give some testimony to the use of scuds.


http://www.youtube.com/watch?v=NRkxMvbLAxg&feature=youtube_gdat...

I found mine in a seasonal local creek that was drying up, and had isolated pools of filimentous algae. Scuds were thick, caught many hundreds in a few minutes with a spaghetti colander.

[Mike Pollard]

Aloha everyone,  I can validate Chris' statement that gammarus will eat roots if they don't have enough food.  In my case, I thought that I had root aphids because all the roots were dying and essentially lopped off at the waterline in my troughs.  I treated the roots with an organic root aphid treatment but to no avail (proving that I did not have root aphids).  I have a huge gammarus population that is out of control - they are everywhere and cover everything.  I can't feed the fish more because it would be too much dead matter for the amount of bacteria that my system can hold (limited by the surface area) and my ammonia levels would go through the roof, doubling the problem.  I could put some other dead matter in for them too eat, but this still is not the solution to the problem.  What I have is an unbalanced ecosystem - there are no predators for the gammarus.  So, I introduced some Asian bumblebee catfish which are direct predators of the gammarus, won't eat my plant roots, and they won't grow too large for the troughs.  I've just started this, and until the catfish get large enough to make a real impact on the gammarus population, I'll throw some dead stuff in the troughs (fruit scraps) to keep them from eating the plant roots.  The only way to control nature is give it what it needs to stay it in balance.

[Jon Parr]

Mike, I don't know if you can get "shellcrackers" there in HI (red ear sunfish), but they will wipe out your gammarus in the raft beds in a few days, and continue to hunt and destroy. 

[Keith Rowan]

i don't know if the shellcrackers would be able to clean them up as well as rosy red minnows, unless you get fry  or fingerlings.. minnows give you the benefit of being a good feed supplement for gamefish..

i haven't had any issues with scuds eating the roots

[George]

Rosy Red, aka Fathead:  I want to get some minnows going but am more interested in Gambusia. 

Keith Rowan said:

 red minnows, unless you get fry  or fingerlings.. minnows give you the benefit of being a good feed

[James Keller]

I just gathered about 30 scuds from the same creek behind my house that I captured my trout in.  I put them in the sump tank last night, and I just checked on them today.  So far so good!  The scuds are naturally occurring here in small creeks and rivers in Jackson, WY.  I have no idea exactly what they are, but I'm hoping that they will be able to keep the solids from building up too much in the sump tank.  I'll hopefully have a positive update in a few weeks!

[Damon Polta]

the gammarus is actually one of the farthest reaching animals on the planet... they're found just about anywhere...

the calcium amount in the system might be dictating the survivability of a colony of gammarus, but also the amount of food for them making it's way into the system is also a big factor... if many of the solids are being caught in a media bed or other means of filtration before the water makes it's way to the trough, they're simply starving....

the control of the gammarus is a key factor in the survivability of the farm, this is true. to easily control the population harvest your rafts regularly. the amount of gammarus that get caught up in the roots and pulled out of the system is a larg enough number to keep over population from happening... the people at friendly aquaponics (while i was there) were harvesting the rafts from any particular part of the system in 6 week cycles. this means every 6 weeks the rafts were removed, roots and all, and at that time the lettuce was cut and sold... while doing this the gammarus would get caught up in the roots and die on the ground... sad i know, but it was necessary, even though at the time we didn't exactly know that...

over time, due to certain circumstances, harvest cycles got interrupted and began to slow drastically... this slowed the regular gammarus genocides and allowed the population to grow over time... over a long enough tie span the amount of gammarus over powered the amount of solid wastes available and they turned on the plants....

so, in short, if you're going to put them in your system make sure you have some plants in there that get cycled through fairly quickly once introduced into the system... lettuces and things of that sort that only need to spend just a few weeks in the system before reaching their harvest time...

in a commercial situation i see them causing less of a problem since things are rotated regularly and often... it's when you let the system sit without finding an easy or effective way of killing the gammarus every once and a while.that people do find problems.