How do I keep this puffer?

I'd like to set up a tank for an Arrowhead puffer. I've been keeping fish for a couple of years, but this is my first oddball fish. What would I need in terms of tank size, set-up and feeding? JASON BRADSHAW, VIA EMAIL

NEALE SAYS: Like all freshwater puffers, the Arrowhead pufferfish,

Tetraodon suvattii, needs good water quality and can be more sensitive to some medications than the usual tetras and barbs, and that means good food, regular water changes, and preventative healthcare are all important. It reaches a maximum size of around 12-15cm but since it is not very active and best kept singly, it doesn’t need a massive aquarium. Although they’ve been kept successfully in tanks as small as 90 l, I’d suggest something around the

125 l mark to provide scope for a varied habitat while usefully reducing the pressure on water changes to keep nitrate levels low — the increased water volume means nitrate will accumulate more slowly.

Aim for nitrate levels below 20 mg/l, and certainly no higher than 40 mg/l. Change 20-30% every week or two, but this might not be adequate if you use a small tank or overfeed.

So far as biotope goes, Tetraodon

suvattii comes from rivers with relatively strong water currents. High oxygen levels will be important, but the water flow doesn’t need to be turbulent. It likes to dig into the sand, so a smooth, sandy substrate, such as pool filter sand, will do the trick nicely. From there, it lurks in wait, ready to lunge at any passing fish. In the wild it mostly eats small fish, but likely takes nips out of bigger fish from time to time. It will also take shrimps, worms, and insect larvae given the chance, and as such hasn’t proven to be difficult to keep, though wriggling live foods may be needed with newly imported specimens. With time they can be weaned onto frozen meaty foods. Prawns and mussels are cheap, but rich in thiaminase, which leads to vitamin B1 deficiency, so they should be fed sparingly. Instead, try earthworms, gut-loaded river shrimp, cockles, squid and white fish fillet.

Tetraodon suvattii doesn’t have such fast-growing teeth as its more omnivorous relatives, so you’re less likely to have to deal with overgrowing teeth. On balance, this makes this species a bit easier to keep than some other puffers, such as Colomesus

asellus, which is notorious for its fast-growing teeth and needs a carefully managed diet to do well. Once you get past water quality your puffer should do well, given sufficient space and the right diet.