Monitor Lizard Diet Guide: Feeder Insects for Savannah, Ackie & Asian Monitors

Monitor Lizard Diet Guide: Feeding Savannah, Ackie & Asian Monitors

Monitor lizards (Varanidae) are obligate carnivores with high metabolic rates, powerful digestive systems, and an intelligence that makes them engaging but demanding captives. Their dietary needs vary significantly by species — a 12-inch ackie monitor eats very differently from a 5-foot Asian water monitor. But all monitors share one critical requirement: lean, high-protein feeders with adequate calcium.

The #1 dietary mistake in captive monitors is feeding too much fat. Fatty liver disease and obesity kill more captive savannah monitors than almost any other single cause.

Diet by Species

Savannah Monitors (Varanus exanthematicus)

Savannah monitors are the most commonly kept — and the most commonly misfed — monitor species. In the wild, they are insectivores that eat primarily invertebrates: beetles, millipedes, snails, and scorpions. They are NOT rodent specialists, despite what outdated care guides suggest.

Critical: Savannah monitors should eat insects as 80-90% of their diet. Rodents should be rare treats only (1-2x per month maximum). A rodent-heavy diet causes fatty liver disease — the leading killer of captive savannah monitors. Discoid roaches at 20% protein and 7% fat provide the lean protein savannahs evolved to eat.

Ackie Monitors (Varanus acanthurus)

Ackies are dwarf monitors — active, intelligent, and entirely insectivorous in captivity. They eat proportionally more insects relative to body size than larger monitors and can be fed more frequently.

• Primary diet: Discoid roach nymphs (medium-large), 8-15 per feeding, 4-5x per week
• Calcium: BSFL 10-20 per feeding, 2x/week
• Low-fat variety: Silkworms 3-6 per feeding, 1-2x/week
• Enrichment: Hornworms 1-3 per feeding, 1x/week
• Occasional: Pinkie mice once per month maximum for adults

Asian Water Monitors (Varanus salvator)

Large species (potentially 6+ feet) with high caloric needs. Juveniles eat primarily insects; adults eat insects, fish, eggs, and occasional rodents.

• Juveniles: Bulk discoid roaches (20-40 per feeding), BSFL, and silkworms daily
• Adults: Mixed diet of large roaches, whole fish (tilapia, silversides), hard-boiled eggs with shell, and occasional rodents
• Key concern: Even large monitors should not eat rodents at every feeding. Insects and fish provide leaner protein.

Why Roaches Are the Perfect Monitor Feeder

Discoid roaches are the ideal monitor lizard feeder because monitors evolved to eat invertebrates — not rodents. Roaches provide:

• 20% protein at only 7% fat — the lean protein ratio monitors need
• Gut-loadable — feed roaches calcium-rich vegetables to boost nutritional value before feeding
• Available in bulk — monitors eat large quantities; roaches can be ordered in bulk at lower per-unit cost
• 6-12 month shelf life — buy large orders less frequently
• Stimulating prey behavior — roaches run, triggering natural hunting and enrichment

Common Monitor Diet Mistakes

• Rodent-heavy diet: The #1 mistake. Mice and rats are 20-30% fat. Monitors fed primarily rodents develop fatty liver disease, obesity, and shortened lifespans. Insects should be the dietary foundation.
• No calcium supplementation: Juvenile monitors growing rapidly need enormous calcium. BSFL + calcium dusting on roaches prevents MBD.
• Feeding daily as adults: Adult savannah and water monitors should eat 3-4 times per week, not daily. Overfeeding causes obesity.
• Only one feeder type: Variety prevents nutritional gaps. Rotate roaches, BSFL, silkworms, and hornworms.

Shop bulk feeders for monitors: discoid roaches | BSFL | silkworms | hornworms

— Matt, Founder, All Angles Creatures