Largehead lizardfish

Where they come from

Largehead lizardfish show up across the Indo-Pacific, hanging out on sandy patches between coral heads and along reef slopes. You usually see them parked on the bottom like a little torpedo, waiting for something careless to swim by. Dawn and dusk are their busy hours.

Setting up their tank

Give them room. They are ambush predators that like a wide, open floor, not a wall of rock. A 6 ft x 2 ft footprint (180 gallons or larger) makes life a lot easier. Smaller tanks work for juveniles, but they grow and they eat like a real predator.

• Substrate: fine sand, at least 2-3 inches. They like to settle in and sometimes shimmy partially into it.
• Rockwork: keep it low and stable with open sand lanes. Think perches and shade, not cliffs.
• Flow: moderate overall, but keep some calmer zones along the bottom so they can sit without getting blasted.
• Lighting: moderate or even on the dim side. They are happier under softer light with shaded spots.
• Lid: tight-fitting with all gaps covered. They can and will launch if startled.
• Filtration: heavy. Big skimmer, strong mechanical, and plan on frequent sock or floss changes. Predators are messy eaters.
• Water: 1.023-1.026 SG, 24-27 C (75-81 F), pH 8.1-8.4, 8-11 dKH, nitrate kept reasonable (<30 ppm). Good oxygenation helps a lot.

What to feed them

They are piscivores first, but you can get them on frozen. Most new imports only take live at the start. I use gut-loaded ghost shrimp or tiny salt-tolerant mollies to break the ice, then switch to dead foods.

• Good staples: silversides, lancefish/sandeels, pieces of marine shrimp, squid, and fish fillet.
• Tools: long feeding tongs. Wiggle the food a bit and let it drift along the sand like a careless goby.
• Schedule: juveniles every other day in small portions; adults 2-3 times per week. Overfeeding leads to fatty liver and a lazy fish.
• Supplements: soak foods in a vitamin/HUFA additive once or twice a week.
• Variety: rotate. Too much silverside can be a thiaminase problem. Mix in shrimp, squid, and non-thiaminase fish. Avoid freshwater feeders like goldfish.

How they behave and who they get along with

Think patient ambush hunter. Most of the day they sit still on the sand, then burst forward like a spring. They are not mean for the sake of it, but if something fits in that mouth, it is food. They ignore very large tankmates that they cannot swallow, and they spook if harassed by hyperactive fish.

• Best kept single. They can get testy with their own kind unless you have a huge footprint and introduce carefully.
• Tankmates to consider: larger, robust fish that stay midwater or are simply too big to be a snack. Examples: large tangs, rabbitfish, puffers, big angels. Avoid fin-nippers that will pick at a resting lizardfish.
• Tankmates to avoid: anything small or slender (wrasses, gobies, anthias, chromis), decorative shrimp and crabs, small eels, and slow fancy fish that might get ambushed.
• Behavior notes: mostly crepuscular. They may change perches as lights ramp up or down. They can jump if startled by maintenance.

Breeding tips

Not a home aquarium project. They are broadcast spawners with tiny pelagic larvae that drift and feed in the plankton. No reported captive pairings or rearing that I know of in hobby tanks. Enjoy them as a single display fish.

Common problems to watch for

• Refusing frozen food: very common early on. Use live to start, then offer fresh-thawed on tongs while they are in hunt mode. Be patient but consistent.
• Mouth injuries: happen during netting or from crashing into rock. Feed softer foods for a while and avoid rough rock edges where they perch.
• Internal parasites: many wild-caught predators carry them. Quarantine and consider deworming with praziquantel and/or metronidazole under guidance.
• Jumping: startled during water changes or at lights-on. Keep the lid tight and ramp lights slowly.
• Bacterial issues from dirty substrate: they sit on the sand a lot. Siphon detritus and keep oxygen high to avoid festering pockets.
• Medication sensitivity: go easy with copper or formalin. Quarantine first so you have treatment options without nuking the display.
• Obesity and fatty liver: feeding daily long term will shorten their life. Stick to that 2-3x weekly adult schedule and keep portions reasonable.