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Question on cyclops and seed shrimp in infusoria


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I have an infusoria culture which I have done with green water, it is 3-4 months old and has been fed with yeast when it starts to lose the green in the water, daily stirring of water. It also has java moss bits that I get from cleaning out the fry tanks. I have put it under the microscope today and have identified a large amounts of what I can guess are seed shrimp. They kind of look like pac man every now and then when they move and included picture below. Also have a video of it pacmanning accross the slide but cant upload it here. The white bits are light from the scopes light. The other pic is I am guessing is a cyclops when compared to the internet picture I found. I have also identified elongated paramecium within the culture. So my question is will the seed shrimp and cyclops be safe to feed to the fry? The fry I have are Danios, Angels and tetras and range from a week old to 3 weeks old. Not sure if cyclops eat fry. These are also less than a pinhead in size not magnified.

My Pics off microscope




Seed Shrimp



Pic off internet

Freshwater copepod (Cyclops) female with eggs

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I’ve had colonies of seed shrimp at various times, and unfortunately they’re too tough for young/small fry to eat. My ricefish couldn’t eat them until they were more than halfway to adult length.

Cyclops won’t hurt your fry (that I know of) but they will predate infusoria. So just keep an eye on the quality of the culture.

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what is the difference between cyclops and seed shrimp?  I have one of them in my tank and need to understand why (healthy ecosystem, I get it).  It's likely due to substrate cleaning regime? Extra junk in the substrate being there?  Is there a movement trait or light trait to determine the difference between the two?

for clarity, the thing in my tank looks like cyclops. Not sure what the options are, but that's the body shape.

It is very likely I have both.

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Seed shrimp or ostracods are little crustaceans with a clam like hinged shell in place of claws. They feed by moving through the water column, fanning their little legs through the gap in the shell. There's a range of sizes. Smallest I have seen are a bit smaller than sesame seeds, I'm culturing some in an old Kirkland Mixed Nuts jar from Costco. Vernal pool specialist organism, so they appear in puddles in your yard from time to time. Mine are from a water feature in the backyard that hasn't been working in over a decade. Largest I have seen/kept were about 1/4" long and reddish, you could really see the details on them. I'd call that size "clam shrimp", but I've seen them also called seed shrimp. I ordered those from some guy in Kansas City over Ebay. They do pretty well, but I lost all mine in a new tank PH crash when their shells dissolved. Green water and yeast are your go-to foods. Their cysts can migrate into shrimp tanks from plants/soils, and they do well on aquasoil substrates.

Cyclops on the other hand are little predators. They'll actively take on things roughly their size. I have a number of some species of these that snuck in with my seed shrimp culture. They take out baby seed shrimp and any infusoria they can find. My adult cyclops are actually smaller than the seed shrimp though, so they don't seem to bother the big adults. Those little polyps on the sides of the tail are egg sacks, so they breed fairly quickly if there's food.

You can find YouTube vids on both of these creatures, but the common themes seem to be how to get rid of them. Shrimp keepers seem to be convinced they'll reduce their tank yield by competing with the shrimplets. My white clouds and neons both seem to enjoy whichever of these get dropped into the main tank. They really seem to relish hunting them down if they venture into open water. I keep these as a small number of live-food projects I've got going that I'm sure I'll end up using, I just haven't quite worked out how. Safe to feed to fry depends a lot on whether the fry can swallow them whole or not. I seem to remember one of Bentley Pascoe's livestreams mentioning he's got some rainbow fish whose mouths open wider than their throats can handle.


{EDIT} Remembered something else that might be of use. In one of Dan's Fish livestreams, Leo209_Aquatics asked about culturing seed shrimp. Dan apparently does them in a small aquarium, with a sponge filter. Keeps them like fish. Can't remember the exact livestream, but I'm pretty sure it was one of November's. I do mine a bit differently, as I followed the "Random Bits" channel advice on culturing mine.


Edited by Comradovich
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