Neale advises a reader who wants to know if a Blue armoured shrimp would be compatible with his whiptail catfish…
Q) I have been wanting to keep a Blue armoured shrimp for a while now but was unsure as to whether it would be compatible with my whiptail catfish. I’m not entirely certain as to what species of whiptail it is but I think it’s a Planiloricaria — I’ve included a picture of the fish from when it was first purchased. Since the catfish buries itself throughout the day and swims about at night, I wondered if perhaps this would lead to them either bumping into each other or problems between them. The whiptail is quite placid and doesn't seem to mind other catfish lying on top of it, but I’m unsure whether it would be harmed if the shrimp walked across it. The tank is a 240 l tank with gouramis, panchax and a few other small fish, so there is plenty of room. Please could you advise on whether this would work?
BRENDAN, VIA EMAIL
A) Neale says: Assuming the Blue armoured shrimp is Atya gabonensis, sometimes called the Blue fan shrimp or the Vampire shrimp, there's no particular reason to be concerned. Your catfish is a harmless deposit feeder that likes to sift sand to extract morsels of food such as worms and insect larvae. Wild fish likely consume a certain amount of organic detritus and algae, too. In any case, while carnivorous towards very small benthic invertebrates, they are otherwise totally benign, and even at moulting time your shrimp should be safe.
Conversely, your fan shrimp is primarily a filter feeder in the wild, naturally orienting itself into the current and using its modified appendages to catch any particles of food that drift by. In captivity they sometimes struggle to get enough to eat. Being adapted to feed on plankton, they aren't good at competing with other animals for any food sitting on the ground.
Yes, they can feed from the substrate if they need to, but they do so slowly, and are probably best kept in tanks where it's possible to direct filter feeder food (such as that sold for reef tanks) or suspensions of 'baby fish food' (like Liquifry) directly into their fans. A turkey baster is a very convenient way to do this.
Besides sufficient calories, it also needs calcium for its shell and some iodine as well for successful moulting. There are foods for pet crustaceans out there that cover these bases, and they are well worth regularly including in its diet.
As the shrimp and the catfish occupy very different ecological niches and feeding strategies, they should ignore one another. The only potential risk might be if the shrimp started pecking at the eyes or trailing fins of the catfish, but I don't think this is very likely. I have kept smaller shrimp and whiptail species together, and while the shrimps climbed over the whiptail, neither seemed bothered by this. I'd focus on ensuring both species have enough to eat.