Neale provides an answer as to why some species are still wild caught and whether there is any risk from keeping wild caught fish.
I recently bought a group of eight marbled hatchetfishes (Carnegiella strigata) for my tank. However, I’ve since discovered that these fish were wild caught. Are they common fish in the wild, as I'm worried about any impact buying wild fish will have? Do fish farms not breed all the common aquarium fish?
Also, being wild caught, will they be likely to pass anything risky onto my other fish?
DAN WADE
Neale Monks's advice on buying wild caught fish
Let’s do the second question first because it’s easier to answer. Generally, a good retailer should have quarantined new stock for at least a short while before putting them on sale. They’ll check they look healthy, are feeding well, and aren’t showing obvious symptoms of diseases. Common diseases that fish stores look out for are whitespot or velvet and if necessary, they’ll treat them as well.
The gold standard in fishkeeping is to assume that any new livestock is a carrier, even if isn’t showing any signs of disease. Quarantining new fish is the best way to go. A separate tank can house new fish for anything up to a month before adding them to the display tank.
In practice, few casual aquarists do this, but it’s still a good idea to buy only livestock that looks healthy. Once home, keep a close eye on the new fish. If a fish disease, like whitespot, rears its ugly head, you can start medicating the fish immediately.
Related article: Why hatchetfish tick all the right boxes.
Why are fish still wild caught?
Your first question is harder to unpick. For tropical freshwater fish something like 90-95% come from fish farms. With regards to value, the percentage of trade based on farmed rather than wild caught fish is similar.
Almost all the angelfish, guppies, and danios that are traded every year are captive bred, for example. Indeed, you’d be hard-pressed to find wild specimens on sale – and if you did, their price would reflect this!
People have successfully bred one or two species of hatchetfish in captivity, but it’s not a regular occurrence. Plus, the tiny size of the fry means that feeding them isn’t straightforward.
The captive breeding of hatchetfish appears to be similar to tetras, where many species come from fish farms. So, why aren’t hatchetfish farmed as well?
Related article: Where do our aquarium fish come from?
The answer is probably down to economics rather than difficulty. The demand for the fish needs to justify the expense involved in setting up the farm. These are complicated and labour-expensive undertakings. Neons, to take an obvious example, will amply repay that investment, but marbled hatchetfish, not so much.
Neon tetras are incredibly popular due to their colour and outgoing behaviour. Photo by Shutterstock
They’re small, somewhat delicate fish with understated markings. While they’re good aquarium fish, they’ll never be as lucrative as the more ‘bread-and-butter’ species with bright colours. So, for the relatively small market that wants them, importing wild caught specimens, even if a bit more expensive, will do the job.
This holds true for many of the species collected from the wild rather than farmed. While they can spawn in captivity, it’s just not worth the bother given the small volume of sales.
The impact of collecting tropical fish on wild populations depends a lot on how people manage the fishery. Generally, small, prey-sized species like hatchetfish can tolerate low intensity collection without problems. Their natural mortality in the wild is high, and they produce lots of fast-growing offspring.
Certainly, things like deforestation, habitat loss, and the abstraction of water are going to be much bigger threats. The introduction of exotic species, such as tilapia and carp, into local waters can also have an effect. You can even argue that attaching economic value to fish populations gives an incentive to care for these waters. This, in turn, ensures all the native fishes prosper, not just the small number of species that aquarists are interested in.
To learn more about the sustainability of aquarium fish collection take a look at Project Piaba. Their focus has been on the Rio Negro, and the wonderful cardinal tetra. Scientists have studied this fishery since 1989 making it one of the most well-studied fisheries of its kind.
This question was fish published in the July issue. Check out our subscription offers so you don't miss an issue!