Ask in a shop for an algae eater and you will usually be pointed at a pleco. The trouble is that “pleco” covers everything from a 10 cm cave-dweller to a half-metre monster, and the cheap ones on the bottom shelf are very often the monster. The bristlenose pleco, sold as Ancistrus sp. or Ancistrus cf. cirrhosus, is the one that actually belongs in an ordinary home aquarium. Mine spend their days rasping the glass and the wood, spawn in caves without being asked, and have never outgrown their welcome. If a suckermouth catfish is going in your tank, make it this one. ...

The betta, Betta splendens, is probably the most mistreated fish in the hobby, and not out of malice. Shops sell them in cups, the internet is full of vase setups, and the myth persists that because wild bettas live in puddles, a jar on a shelf is fine. Wild bettas live in rice paddies, marshes and slow floodplains, which are shallow but enormous, warm all year and full of cover. The puddle story comes from the dry season, when getting trapped in one is the worst thing that can happen to a betta, not its preferred address. I keep bettas on my desk in proper heated, filtered tubs, and the difference between a betta in decent conditions and one in a bowl is the difference between an active, curious, flaring fish and a listless one clamped in a corner. ...

Cherry shrimp were one of the best additions I ever made to my fishroom, and one of the cheapest per animal once the colony got going. Neocaridina davidi, to give them their proper name, are small dwarf shrimp from Taiwan that have been selectively bred into red, orange, yellow, blue and near-black lines. Buy ten, look after them, and within a year you can have hundreds without doing anything clever. In my very hard tap water, around 22 to 23 dGH, they do not merely survive. They moult cleanly, colour up well and breed constantly. If your water is hard and you have been told it limits you, shrimp are one of the animals it actively favours. ...