Scorpion Fish, Catfish, and Eels

Another fish that depends on camouflage is the scorpion fish (family Scorpaenidae), a heavy animal with ridges and spines on its back. The fins and spines contain venom that protects this fish from predators. Warts and skin tassels covering its body make the scorpion fish look like part of the reef. This animal waits patiently for prey to get close then literally sucks it in.
scorpion fish (family Scorpaenidae)
Scorpion fish (family Scorpaenidae)

The bandtail puffer (Spheroides spengleri), like other species of puffers, has a very different way of protecting itself. By filling its abdomen with water, the little fish can inflate its body, giving it a bigger and fiercer appearance. In addition, an inflated fish is more difficult for a predator to swallow than an uninflated one.
bandtail puffer (Spheroides spengleri)
Bandtail puffer (Spheroides spengleri)
A close relative, the porcupine fish (Diodon hystix), uses the same mechanism when it feels threatened. Porcupine fish are covered with damaging sharp spines that deter predators. Shallow reef waters and turtle grass beds are some of the places where porcupine fish hunt for prey. Both porcupine fish and bandtail puffers have two fused teeth in each jaw that give their mouths a beaklike appearance. This type of jaw is efficient at crushing the hard shells of crabs and mollusks.
porcupine fish (Diodon hystix)
Porcupine fish (Diodon hystix)
The moray eel (family Muraenidae), seen in the upper color insert on page C-7 has a fearsome reputation because its gaping mouth is full of sharp teeth. In reality members of this group are shy and retiring animals that spend their days hiding in reef crevices. Morays hold their mouths open so that water can be pumped over the gills. Their long, muscular bodies are highly modified for living among rocks and coral. Morays are scale-less, and both their pectoral and pelvic fins are absent. In addition, their remaining fins are fleshy ridges that are covered with thick skin. This body streamlining is an adaptation that helps morays navigate through the narrow passages of the reef structure. When they emerge at night to look for invertebrates, they swim by moving their entire bodies back and forth in an S-shaped pattern.
The moray eel (family Muraenidae)
The moray eel (family Muraenidae)
Another long, fierce-looking reef fish is the great barracuda (Sphyraena barracuda), a slender animal whose body ends in a pointed head with a narrow snout and sharp teeth. Barracudas usually hover around the edges of reefs, waiting for prey to appear. Once a potential meal is spotted, they rush forward aggressively to grab it. Some barracudas reach impressive lengths of 6 feet (1.8 m).
The great barracuda (Sphyraena barracuda)
The great barracuda (Sphyraena barracuda)
 The only catfish on the reef are the coral catfish (Phetusus angularis). These small fish have venomous notched spines near their dorsal and pectoral fins. When young, coral catfish school, or live in groups, by the hundreds near the reef floor; however, as they get older, they form smaller groups of about 20 animals. Maturity also changes they way they look. Young catfish are black, but adults develop a brown color with yellow or white horizontal stripes. They feed on crustaceans, mollusks, and worms, which they find by stirring up the reef floor.

catfish (Phetusus angularis)
Catfish (Phetusus angularis)