Considering the size most are sold at it would be OK for a while, but if you get the hang of it and keep it alive and well these grow to nearly 10" long or more, roughly the size of a Nerf football, meaning of course hat it would eventually need a much larger tank.
Porcupines have a large biomass compared to most fish, meaning that they are often half as wide and high as they are long, roughly 4-5 times he bulk of similar length fish and thus use far more air.
Due to their method of feeding, which is to thoroughly chew up everything, they often release extra oils and such ino the water as well, often eating as much as 2-3 normal fish in the size range as well....keep in mind that what goes in eventually comes back out, and these guys can really make or break the filteration system.
Yes, they're cute and with loads of personality, but need a larger tank in the end.