Seeing one of these fish at first glance you may think you have just seen a lizard sitting on the seafloor, but despite their reptilian appearance lizard fish are definitely a fish. They belong to a family of fish with prehistoric roots called Synodontidae which consists of more than 70 different species with 27 of those being found in Australian waters. Most species are quite small however some can reach up to 70 centimetres. These fish are not particularly valued from a commercial standpoint as they are not considered good eating fish although they are often caught as bycatch in trawl nets. However they do have more value in the recreation dive industry, their large comical mouths make them a fun character to spot on the reef.
Lizard fish have quite a wide distribution and they can be found in both warm tropical waters and cooler temperate waters all over the world. Their habitat range is also quite varied, they are benthic (bottom dwelling) fish that can be found in the sandy, buddy bottoms of estuaries and inshore bays, coral reefs and even offshore habitats. Most species prefer shallow waters however some have been found inhabiting depths of around 300 meters.
The name lizard fish comes from their reptilian like head. They also have a large mouth that is full of many tiny needle-like teeth which gives them the appearance of having a perpetual toothy grin. This mouth has resulted in a common nickname, grinners. The bodies of the fish in this family are characteristically long and sender, having an almost cylindrical shape. Their colouring is reflective of their bottom dwelling lifestyle, they range from browns, creams and greys to reds, greens and blue and all have a mottled, spotted patterning to help them blend in on the seafloor.
These guys often live in pairs and are not very social fish, though they may live in close proximity to others they will generally only interact with each other during spawning. Even during spawning they are not in particularly close contact with others of their species as fertilisation is external. The female will release her eggs along the reef and the male will follow behind fertilising them as he goes. There is no parental care involved with the fertilised eggs and they will settle on corals, rocks and sea weeds. Once the eggs hatch the larval lizard fish will live in the water column as zooplankton and be carried around by the oceans currents towards shallow habitats where the developed juveniles will then descend and begin their lives as bottom dwelling fish.
As their toothy appearance would suggest these fish are most definitely carnivores. They are ambush predators, using their excellent camouflage they will settle on coral, rocks and sometimes even bury themselves in the sand with only their eyes showing, to wait for passing prey. Once they spot something they want to eat the lizard fish will dart up and snatch it out of the water column, this often happens so fast that the unsuspecting prey does not even see the lizard fish coming. The preferred prey of these aggressive predators are small fishes such as sardines and anchovies and also a variety of crustaceans like small shrimp.
Here in the Whitsundays we have quite a healthy population of lizard fish living on our fringing reefs. If you look closely enough while on snorkels you may be able to spot them trying to blend in on the reef. Once they have noticed you watching them these guys will quickly move from hiding spot to hiding spot, playing a game of underwater hide and seek to try and avoid your gaze. If fishing is what you have come to the Whitsundays for you may still have many interactions with these fish without even knowing it. Those tiny frustrating nibbles a lot of fishermen feel on their lines just before their bait, particularly shrimp, disappears is usually these cheeky grinners trying to get an easy meal.