Amano shrimp – aquarium cleanup crew

Amano shrimp have a well-deserved reputation as efficient algae eaters.  These small mostly translucent freshwater shrimp won’t hurt live plants or animals but enjoy chowing down on algae, particularly soft, stringy green stuff.  With their small size and 10 legs they can pretty much get into nooks and crannies to do their cleaning job.  They add negligible bioload to an aquarium so the usual recommendation is one amano shrimp per 5 litres of water, which is the approach I took here.  Similar to nerite snails, although the adult shrimp live in fresh water, they need to move to slightly brackish water to breed successfully.  That generally means you don’t have to worry that you will be innundated with baby amano shrimp.

Amano shrimp appearance and characteristics

Near as I can tell the amanos have quite strong sexual dimorphism:  the males are smaller and more translucent, while the females are quite a bit larger, and darker in colour.  If you just want males, aim for getting the smaller ones.

The amanos are generally quite active although they do seem to enjoy being in high places on hardscape.  The top of the mountain sculpture in the Fireplace Aquarium is a very popular hang-out for them.  They can also be found on the leaves of aquarium plants, on the substrate floor, and on various bits of submerged kit in the aquarium such as heaters, powerheads and CO2 lines.  They can’t really grab onto flat vertical surfaces which means they aren’t very effective in removing flat algae from aquarium tank walls.  They have a reputation for being “jumpy” so if you have an uncovered tank you might consider dropping the water level down a touch so they can’t leap out to their death. 

Amanos will, from time to time as they grow, shed their exoskeleton.  If you see what looks like a dead shrimp with fish nibbling on it, it may simply be from a moulting so no need to panic.  I have heard of amanos getting sucked into filters (not a problem in the Fireplace Aquarium) and you can get mesh-style “shrimp guards” to keep them from getting pulverised inside powerheads, but although my powerhead has no such guard on it and although the shrimp do take an interest and not infrequently perch upon it, I’ve never had one get tragically caught up in it.  They seem to be pretty clever about things like that.

You sometimes hear that amanos can by ‘shy’ but that is not my experience with them.  I suspect that in many cases what is interpreted as ‘shy hiding behaviour’ is in reality ‘escaped from the tank’.

Weird amano shrimp behaviour

I noticed a very interesting behaviour once during a major water change… the water level was way down and I was refilling by having water cascade down the back wall of the aquarium and every single amano shrimp made a mad and sustained (unsuccessful) effort to “climb up the waterfall”.  I can only surmise this was a triggered behaviour based on river water flow – if the water looks like it’s running dry better head upstream to the source!