Can you imagine changing your shape and distorting your body into a big round ball when you get frightened or startled? Such is the life of puffer fish and porcupine fish, both commonly known as blowfish. These creatures inflate themselves whenever they feel threatened.

Bloating up by gulping water or air into their systems, these fish make themselves appear bigger with the intention of discouraging predators. This is their primary defense mechanism because they don’t swim very fast, even when deflated. Inflated, they just waddle around the water.

If they are eaten before they get the chance to inflate, they will do so in the mouth of the predator, usually resulting in both fish dying. Not exactly the desired outcome for the blowfish, but at least it went down trying.

Puffers and porcupine fish look quite similar although porcupine fish, as their name implies, bear rigid bony spines on their skin that pop up as the fish bloats with fear. Some of the 100 or so species of puffers may have a prickly texture when they are bloated, but nothing compared to the bony spines of the 20 species of porcupine fish. The mouth of the porcupine fish generally forms a much sharper beak, but the spines give it away.

Blowfish Are Hardy and Compatible

Blowfish are a sought-after aquarium species because they are generally hardy and compatible with most other fish and are only aggressive when threatened. Despite their hardiness, these fish shouldn’t be kept by a novice marine fish keeper because their voracious appetites limit the kinds of species you can have in your tank.

In the wild, however, they are having a difficult time competing with threats to their coral reefs. The aquarium trade does its share of damage to the fish, but they are also a highly sought-after delicacy in Japan. Certain species of blowfish are used by the Japanese to prepare a very special sushi known as fugu. Because many species of blowfish have toxic flesh, the sushi chefs that prepare this dish must be highly trained. If the chef slips, the gourmet can expect death.

Although most blowfish get along with other species (most of their aggression is reserved for others of their species), they will not turn down an invertebrate meal. They seek out small sea urchins, crustaceans and mollusks, and with their powerful jaws and teeth easily crush any hermit crab’s shell. They can be hard, therefore, on a reef aquarium where lots of invertebrates reside.

These fish will eat whatever you feed them – frozen or fresh shrimp, mussels or clams, flakes, fish or brine shrimp. Give them a varied diet and feed them a couple of times a day.

They require a pH of between 8.1 and 8.3, and they prefer water temperatures of between 77 and 79 degrees Fahrenheit. Keep the specific gravity at about 1.021 to 1.024 and make sure to do at least a 15 percent to 25 percent water change about every 10 to 14 days in an established system.

Types of Puffers and Porcupines

The porcupine fish (Didon hystrix) is commonly available. The fish is grayish white with dark spots on its body.

The reticulated puffer (Arothron reticularis) is available from time to time. It has a brown reticulated pattern on a white body. This fish comes from the Indo-Pacific near reef areas.

The stars-and-stripes puffer (Arothron hispidus), so called because of the star-like markings on the upper portion of its body and the stripes on the lower portion, is an absolute disaster in reef aquariums since it has a penchant for eating just about every invertebrate found there. It is a great fish in a fish-only tank, however.

Another popular porcupine fish species commonly found in aquaria is the Caribbean striped burrfish (Chilomycterus schoepfi). It has a white body with brown stripes, some large brown spots and green-blue eyes. It’s called a burrfish because its spines stick up all the time. This species is particularly popular not only because it’s very hardy, surviving a wider range of conditions than most other blowfish, but it can also become rather tame over time, often accepting food from your hand.

If you’re going to get blowfish for your aquarium, it is best to get them young. They seem to do better in tanks when they were introduced as juveniles.