Backyard Aquaponics
A place to discuss aquaponics

Has anyone run into problems with ostracods and other zooplankton

I know alot of APers have flood and drain systems, but does anyone with raft type beds or NFT have problems with ostracods? I noticed them in my raft hydroponic type beds awhile back but they didn't seem to be in large numbers or causing problems. But now they have increased greatly and I read they eat bacteria, algae, and fine root hairs. I did notice them grazing the fine root hairs of my bibb lettuce plants some but they weren't stunting the plants any. And under the microscope they appeared to be removing bits of algae from bacteria so I figured they were beneficial and I didn't worry about them but now the ammonia in my almost 6 month old system has spiked and is killing my Tilapia. I know that the ostracods reside on the sides of the plastic grow beds were the bacteria grow but I'm not sure if they are grazing it. Are ammonia spikes in systems later after cycling common? Or are the ostracods having a severe impact on the bacterial population by grazing away the bacteria faster than it can regrow?

If it is the ostracods, does anyone know how to control them? As far as everything I've researched no fish will control them because they can pass thru the digestive tract and other animals that eat them are all marine that I have found.

Before jumping to the conclusion that the ostracod's are the cause of the ammonia spike, first check all other water tests. The most likely cause of an ammonia spike in a long cycled system that is not exposed to temperature drops is pH dropping too low for the bacteria that converts ammonia to nitrite. Other likely causes for spikes include solids building up somewhere and rotting, a dead fish hidden somewhere in the system, additions of chemicals or water with enough treatment to kill off or hinder some of your bacteria, or some family member having been trained by the fish to give them extra food without your knowledge.

So, what's your pH

My pH has been steady at around 7.2-7.6. It can't be a dead fish, the supplements I've been adding have never been a problem, and my family doesn't feed my fish even when I ask them to when I'm gone lol The only reason I suspect the ostracods is because all other variables that I can think of have stayed the same except for the increasing ostracod population. I will also need to take care of them anyway even if they aren't the cause of the ammonia spike because they are causing increasing damage to my plant roots and I'm guessing that will become a serious problem.
So I guess advice on the ammonia spike and/or the grazing ostracods would be appreciated

Hum...
I really don't know anything about ostracod. Actually your post is the first time I'd heard of them. Perhaps you need a few prawns in your DWC to eat them or something? Good Luck finding an answer.

Ya I don't think they are ever a problem in flood and drain beds but I know that they have been mentioned as a problem in the Virgin Islands system run by James Rakocy. I've been doing lots of research on ostracods but I hadn't looked into prawns so I'll check into that. Thanks

Actually, UVI has had problems with zooplankton in the past.


SRAC Publication No. 454 November 2006 Revision
Recirculating Aquaculture Tank Production
Systems: Aquaponics—Integrating Fish and
Plant Culture
Similarly, blooms of zooplankton, especially ostracods, will consume
root hairs and fine roots, retarding plant growth. Other pests are tadpoles and snails, which consume roots and nitrifying bacteria. These problems can be surmounted by increasing water agitation to prevent root colonization by zooplankton and by stocking some carnivorous fish such as red ear sunfish (shellcrackers) in hydroponic tanks to prey on tadpoles and snails.

One aquaponic DWC, that was raising Tilapia, had Gymnocorymbus ternetzi (Black tetra) to eat the ostracods in the grow ponds. There are a few other tropical fish that also eat them but not many. You'll have to do a search to find others that may work for you.

Hum, my channel catfish eat snails. I wonder if you could get a few really little catfish fingerlings to live in the DWC to eat the creatures, I know a primary wild food for catfish is supposed to be small crustations? How deep are your DWC beds? Might work if they are at least a foot deep. Catfish would need extra aeration in them probably. Nice thing about channel catfish for that purpose is they don't seem interested in eating plant matter.

I'll look into Black Tetras if they've been used before. I built my beds (when I didn't know what I was doing lol) but I built them for lettuce greens for my experiment and they work pretty well but they're only 6-7 inches deep which would be way too small for any fish very big like catfish other than maybe fry or very small fingerlings. But small tetras might be perfect as the beds are well aerated and if they eat ostracods, there is PLENTY of food.

Make sure you get Black Skirt Tetras, which are omnivores, not Black Tetras which are a different species. Here are posting to show the difference.

The black tetra (Gymnocorymbus ternetzi) also known as the black skirt tetra or black widow tetra is a freshwater fish of the characin family (family Characidae) (which includes all tetras, including the piranha), of order Characiformes. It is native to the Paraguay and Guaporé River basins of southern Brazil, Argentina, and Bolivia.
Growing to about 6 cm (2.5 in) total length, the black tetra has a roughly tetragonal body shape and is greyish in colour, fading from light at the nose to near black at the tail. Two prominent black vertical bars appear just posterior of the gills.
The black widow tetra feeds on small crustaceans, insects, and worms.
http://en.wikipedia.org/wiki/Black_tetra

The black neon tetra (Hyphessobrycon herbertaxelrodi) is a freshwater fish of the characin family (family Characidae) of order Characiformes. It is native to the Paraguay basin of southern Brazil.
This species is of typical elongated tetra appearance; it is of plain basic coloration but with two distinct, adjacent longitudinal stripes, white above black. The eye has two thin but distinctive color bands across the top, red above yellow. It grows to a maximum overall length of approximately 4 cm (1.5 in). Despite its common name, it does not particularly resemble the neon tetra, which belongs to a different genus.
The fish's natural diet consist of small invertebrates and plants.
http://en.wikipedia.org/wiki/Black_neon_tetra

I know the fish name in the wikipedia said "Black Tetra" but it's the petshops that sometimes have incorrect names so if you see what the species looks like than you know what to look for.
BTW, there is also a white version of the Black Skirt, called the "White Tetra" or "White Skirt Tetra". Same species, just a color variation.
http://www.petsolutions.com/White-Skirt ... 01603.aspx

Thanks Angie
If I decide to try them I'll make sure I get the right tetra so my plants don't suffer even further. While I was finding info on the black skirt tetra, I also found the sailfin tetra which eats primarily ostracods and copepods. It is also solitary which might be better for my beds with a few lone fish keeping the population controlled as opposed to a school.
In any case I think I'll do some more research and maybe put some ostracods in a small tank with the tetra I choose to see if they will do the job.

It looks like the tetra family is fairly carnivorous in general- they're all related to Phiranahs.

Keep your results posted, it'll be interesting to see what happens. This is a fairly rare occurance in DWC and I was lucky to run across someone else who had posted this same problem. How do you think the ostracods were introduced into your system in the first place?

I think they came with my Tilapia. Even though I live in colorado where it can get down to -50 F in the winter a few people raise tilapia in earthen ponds fed by geothermal wells. So they probably were thriving in those ponds and I read they can survive the digestive tract of a lot of fish so I'm guessing they came literally in the Tilapia but I also read the cysts can survive dry for a long time so anything that came into contact with my system and got wet may have introduced them.

I'm sorry to hear about your problem. I know that they will next to impossible to eradicate but hopefully, you can keep them under control. Now, you know at least two means of controlling them- predators and aeration.

I am also anticipating the introduction of unwanted flora and fauna once my system is established. For one thing, I won't be building a hoop house to cover the system until winter and for another, there is a multitude of wildlife that is attracted to water environments here, from water fowl to amphibians and flying insects.

Ya its amazing (and annoying) how other species appear in AP being like an artificial ecosystem. My system is indoors in the dining room and I live in colorado where like I said it gets very cold so during the winter things are pretty much dormant but I still managed to get tag alongs lol. Along with trying some tetras (cause its just fun to have more fish) I'm going to get some small commercial air compressors to replace the aquarium air pumps I'm using in my beds to beef up the aeration and hopefully that will help some too.