Will my shrimp hybridise?

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Neale Monks gives his advice to a reader who would like to keep shrimp, but is concerned about interbreeding.

Q) I’d like to keep some shrimp in a heavily planted 20 l/4.5 gal aquarium, ideally a mix of Cherries and black and white bee shrimp. Will they interbreed? I’m using an air-powered sponge filter and there are no fish in the tank.

COLIN, VIA EMAIL

A) NEALE MONKS SAYS: Cherry shrimp, Neocaridina davidi, and bee shrimp (varieties of Caridina cantonensis), shouldn’t hybridise. They’re not closely related, and even if they do try, it’s unlikely their offspring would be viable, let alone fertile. So yes, you should be able to mix them without problems. Cherries are quite a bit easier to keep than bee shrimp, so if this is your fish shrimp tank, I’d recommend starting off with a colony of these and seeing how you go. They are adaptable and willingly eat all sorts of things, not just fresh green algae, making them among the best species for beginners. Once the tank has been running for a few months and has a good growth of algae and other microbes, you could introduce some bee shrimp.

Bee shrimp require water towards the softer end of the range, perhaps 2-5°H, pH 6.5-7.0. If you have hard tap water but don’t have access to a source of mineral-free water (such as RO or rainwater) you may find them difficult. Cherry shrimps, on the other hand, will adapt to almost anything provided extremes are avoided, values between 5-15°dH being acceptable, with middling values in that range being the ideal for breeding purposes.

Unless the tank is in a cold room, a heater won’t be necessary. During the winter as the water cools down the shrimp will eat less and stop breeding, picking up again once the weather warms up in spring. But using a heater is a good way to ensure all-year-round breeding if that’s important to you.

A 20 l/4.5 gal tank could easily hold two dozen Cherry shrimp, the usual rule of thumb being to allow a couple of shrimp per litre, assuming adequate filtration and water changes. More mature tanks with healthy plant growth might handle a few more, and once the tank has been running a few months, chances are you’ll have dozens if not hundreds of juvenile shrimps in the tank as well. What tends to happen after a while is that the population sort of levels off at the carrying capacity of the aquarium, partly because excess individuals fail to find enough food to survive. I’d suggest buying 6-12 adults, and then let nature takes its course.