Right fish to keep cherry shrimp pop under control?

I have a 32g planted tank containing 7 neon tetras, 2 endler guppies, 2 nerites and LOTS of cherry shrimps. About 9 months ago I bought 10 and they’ve since multiplied exponentially. Hard to tell numbers but they are well in excess of 100, possibly 200.

As much as I love them, I’d like to keep their population under control as they are significantly adding to the bioload. To keep the nitrates under 20ppm I currently need multiple ~20% water changes per week. Which is quite stressful for the fish (and me!). The high bioload also resulted in quite a few fish casualties while I was away for only a couple of weeks during the summer…
I was thinking of adding a pair of fish to try to keep the cherries pop under control but without wiping them out (with the ultimate aim of eventually restocking the guppies too once the tank is less overstocked). I think my tank setup should make it possible, with lots of plants and hiding places under/inside/behind a log where fish cannot reach. See picture of my tank attached.

What fish would you guys recommend for this? I would like something that will opportunistically feed on them but without going on a killing rampage.

Currently thinking of getting a pair of Honey Gouramis, or maybe Pearls, which I am told are less aggressive that bigger gouramis (or even dwarfs). My LFS has a pair of beautiful apistos (borellis), and he tells me they are very docile for cichlids… but they ARE cichlids and that is somewhat scary. Would they wipe out the colony?


Any other suggestions? Thank you, I am still fairly new to fish keeping and I’d really appreciate any advice!

 

Have you thought of selling some?

Sounds like you have a good colony going and they are reproducing. We would try to sell them online and lfs

* edit
rather than putting a predator in and maybe the shrimpers will stop producing.

 

Have you thought of selling some?

Sounds like you have a good colony going and they are reproducing. We would try to sell them online and lfs

yes I thought of that, and I would prefer that approach because I love my cherries, but frankly it would be difficult to do in practice. Between work and other commitments I just don’t have the time to get that organised.

also they are not pure red. I like color varieties so I let them mix. I now have reds, whites, transparent ones, brown and striped. I think they are beautiful but buyers prefer purer breeds I think.

 

So the idea is to introduce more fish to keep the cherries under control in order to reduce bioload.

Feel free to share your calculations of reduced bioload by having, let's say, 100 cherries less, but 2 additional fish instead.

The tetras should keep the population eventually in check by hunting down shrimplets. Especially, when you start feeding your tetras (much) less.

And it's very plausible that feeding your fish less also helps lowering nitrates. Most fish keepers feed their fish too much.

PS: mixing neocaridina color morphs results in less color morphs over generations.

 

So the idea is to introduce more fish to keep the cherries under control in order to reduce bioload.

Feel free to share your calculations of reduced bioload by having, let's say, 100 cherries less, but 2 additional fish instead.

The tetras should keep the population eventually in check by hunting down shrimplets. Especially, when you start feeding your tetras (much) less.

And it's very plausible that feeding your fish less also helps lowering nitrates. Most fish keepers feed their fish too much.

PS: mixing neocaridina color morphs results in less color morphs over generations.

Again I’m not very experienced and I went by the numbers I found on the net (attached). Let’s say I have ~150 cherries, if those numbers are right that means my 32g tank is maxed out just with the shrimp. Add roughly 10’ of fish and I’m definitely overloaded.

My thinking, and I could be wrong here, was that if I can cut the numbers down to 30-40 cherries, than the bioload saving would definitely support 3-4’ of extra fish (and more).

The neon tetras have been useless at hunting down the shrimplets. When I first added the cherries I thought the neons would kill any shrimplets but they had hardly any impact. In the first batch of babies, easily 15 made it to maturity. After that it was hard to keep track, but I regularly see babies hiding around the tank.

I think my tank has just too many hiding places and plant/Java-moss to be honest. Which is why I thought a pair of more competent predators might strike a good balance.

(I can try to feed less, but already I don’t think I feed a lot. Every other day a few pellets and/or brine shrimps. Maybe that’s still too much…. Perhaps if I starve the tetras they’ll start doing their job.)

 

The diet of shrimps is different from fish. Their metabolism is different. Their waste is different.

The list is ...how shall I put it....

Perhaps the following is helpful: Im working on a new (river) scape (see image below). The surface area of the tank is 24 by 12 inch. The effective surface area, due to the stones, is perhaps double. But....the tank has only 4 gallons of water (due to the large stones taking up all the space). I think this tank can support the 275 shrimp that is listed in the overview you provided. Especially, if I'd offer complementary food.




If I were you, I would stop feeding your tetra's all together for a while. This is not a silly or mean thought at all. Just stop feeding for a week or so and see if your fish start showing interest in shrimplets.

This is not theory; this is actually a practice I have been following for many years for most of my fish tanks. I only offer my fish complementary food. The other food is "tank produced" (shrimplets, copepods, and other small crustaceans).

Apologies for my blunt responses. It's my character and culture.

 

I can try that for a week and see what happens, thank you. Bit worried about starving the endler guppies, but hopefully they’ll cope… no chance they’ll ever catch a shrimplet

That’s a beautiful tank btw!

 

Thank you. Yours also.

Just to make things clear. I'm not necessarily against adding more fish, especially if they are from the same species, but I'm certain 1) most fish will go after shrimplets if there's a need, and 2) most fish are given too much food by the keeper. This might very well result in too much nitrates and no need for fish to start hunting.

 

yes I thought of that, and I would prefer that approach because I love my cherries, but frankly it would be difficult to do in practice. Between work and other commitments I just don’t have the time to get that organised.

also they are not pure red. I like color varieties so I let them mix. I now have reds, whites, transparent ones, brown and striped. I think they are beautiful but buyers prefer purer breeds I think.

Eventually they will revert back to wild form if not culled etc. Colors will run out slowly even with mixing. But hey its all good. Most lfs that buy locally will buy randoms and wild form as well. Not that they haven't seen them before but you may just throw them a curve ball one day with the combos! Also just selling them yourself can work, bulk deals if you feel overrun. Facebook groups and here as well would be good defending on your location.

Not against adding fish, but removing and separating if thats something your into, then line breeding them...Maybe make some extra cash.
Keep a healthy crowd in this tank for balance. Tetras should grab some shrimplets, they like most fish are opportunistic. But if they are eating food put in then unlikely they will waste the energy but still, they probably have.

 

I'm not convinced the shrimp are causing the nitrate spikes. You said you had lost some fish due to high nitrates. How high was it?

 

Day old shrimp can’t even swim against the current, they just float around at the surface. Any hungry fish will eat day olds.

Fish including endler juveniles will not starve without food for ten days.

I am not sure what you mean by a 20% water change being stressful on fish? Match the temperature and you can change 45% at one time no problem. You can change another 45% after four hours on the same day if you are serious about lowering nitrates .

I am also not convinced shrimp are big contributors to nitrates .

I am also not convinced 40 ppm nitrates is a safety concern for the fish species you have , but that’s your choice if you want them to be 20 ppm and is not part of your question.

The inch per gallon rule is not part of modern fish keeping. Stocking by inches of fish per gallon is not a reliable method.

A ten inch Oscar can’t go in a ten gallon tank. It’s just ridiculous to think inch per gallon means anything. If your local shop started talking that way to you it’s time to find a new shop.

 

When I lost a few fishes while I was away for a couple of weeks the nitrates were well over 40ppm, closer to 80. Part of the issue may be the automatic feeder that fed them daily, but even when I manually feed them more sparingly every other day nitrates rise quickly. Don’t know if that’s what’s causes the death, but it’s as good a guess as I can make given they were all healthy prior to that.

I don’t see what else could be causing the nitrates. The two endlers are tiny, and surely not 7 neons in a 32 inch tank. There is definely shrimp poop everywhere…. Thing is, it’s really hard to know how many shrimps there really are. My driftwood is hollow and there is space underneath it too. There could be way more than I think hiding under there, very possible 150 is low-balling it When the first batch of shrimplets was born, you hardly ever saw one (I thought the tetras got them all) until suddenly a couple weeks later some 15-20 juveniles started timidly coming out of hiding.

I am aware the 1 inch stocking rule is not accurate for large fishes, but I don’t have any large fish nor was I talking about getting large fishes. I thought it was a decent approximation for sub 2inch fish without going into 3D geometry (my tank is fairly well proportioned anyway). If you have a better simple calculation please I would love to know it.

I will be trying to stop feeding for some time and see if the tetras become more aggressive, but my question was really whether anyone can recommend some fish that could be a bit more efficient feeding on the shrimp without going on a genocide mission.

Does anyone have any good suggestion? Would a pair of honey gouramis wipe out the colony?

 

I am trying to help sar98 please don’t take my suggestions the wrong way?

To answer your question about a fish species that eats a few juvenile and adult shrimp without hunting down all of them . I don’t think there is such a creature. I believe the hiding places and cover available for the shrimp is the key to ether no shrimp reaching adulthood or many reaching adulthood.

I use adult cherry shrimp as a live food culture.
I add cherry shrimp to fry grow out tanks and see an explosion of young shrimp when the fry are tiny and being power feed multiple times a day.Then I have seen some species of juvenile fish clean out the young and adult shrimp as the fish grow.



While I definitely don’t think adding a fish is the answer to a high nitrates issue I do have a female betta that is a slow hunter and not very persistent . I am certain each betta behaves differently as some do seem to be more determined at hunting down ever last shrimp.

Are you using a vacuum when you are changing the 20% everyday? How is it possible “there is shrimp poop everywhere “ if you are vacuuming part of the tank everyday?

In short.
I suggest you change more water more often and feed a lot less.

I am almost certain I kill my own fish by feeding to much dry food to often? We all make mistakes.

Final thoughts.
The picture in post #1 shows a nice clean looking tank. The substrate is clean. In that picture it does not seem to have a big build up of mulm and poop.

A snapshot of our 32 gallon lounge tank with an unknown number of shrimp, 20 plus green neon tetras, 5 male endlers, three juvenile Siamese algae eaters and a mystery snail. I do a 45% water change every week, plus random small changes once in a blue moon. Last time I checked there was 40 ppm nitrates in the water before water change day.

 

Thank you Flyfisha, I appreciate you are trying to help and if I came across in a bad way, it wasn’t my intention.

When I took that picture I had recently vacuumed the gravel, which I do every water change. Hence the clean look, but after a couple days the build up start being visible. I have never moved the driftwood as it was difficult to keep from floating off and I am afraid i might not be easily able to put it back, but when I move around the stones once a month the amount of dirt that comes up is unspeakable (as is the amount in the sponge filters at the back to the tank).

Sounds like the nitrate production in your tank is comparable to mine. If I don’t change water for a whole week it creeps close to 40ppm. I normally do 2-3x 20% water changes to keep it around 20ppm instead of 1x 45%. But you have ~3x more fish than me, hence my frustration with the shrimp. I love them, but i’d rather have a few more fish. Tetras hide or sit around a lot of the time and the tank feels empty with just a couple of endlers (bless them) dashing around.

Below is just a random snapshot of my typical concentration of shrimp. I can count at least 9-10 in that small frame (some are wild coloured or transparent and are harder to spot), perhaps someone can use that to give me a better estimates of how many I may have!

I’ll try the starving method for some time. If that fails what I will probably do is try out some of the honey gouramis and if I see too much carnage I’ll return them to lfs.

 

You could start propagating pothos cuttings in the outside of the tank? I don’t believe they remove as much nitrates as some U tube channels would have you believe. But they definitely help especially when you have 20 cuttings in a tank.

Just 4 cuttings in the lounge tank.

An old shot of shrimp and fish having a standoff over the food. I don’t try to count shrimp. You know they started in the hobby as a live food culture ? Not that many years ago that was all they were.