Antarctic dragonfish

Where they come from

Antarctic dragonfish (Vomeridens infuscipinnis) live on the cold continental shelf around Antarctica, usually over sand and rubble in near-freezing seawater. Think dim light, slow life, and long seasons of dark and twilight. They are part of the notothenioid group with natural antifreeze proteins in their blood.

Setting up their tank

Be honest with yourself: this is a project for people who already run coldwater systems or have access to lab-grade gear. I have kept this species, and the life support is the whole game. Heat is your enemy, redundancy is your friend.

• Tank: 180-240 gallons for a single adult; long footprint with tight lids (they can startle-jump).
• Chiller: 1-2 HP commercial unit, plumbed on a closed loop. Target 0-2 C. Have a backup plan.
• Controls and safety: dedicated temperature controller with high/low alarms, GFCI, battery or generator backup.
• Filtration: oversized skimmer, large biofilter (moving bed or big sump media), and strong aeration. Cold water holds oxygen, but fish still demand high O2.
• Flow: gentle across the bottom with slack areas. 4-6x turnover is fine; avoid blasting them.
• Salinity and chemistry: 34-35 ppt, pH about 8.0-8.2, nitrate as low as you can keep it. Keep it stable.
• Lighting: dim and diffuse. They do better under low light with a dusk/dawn ramp.

Aquascape with stable rock piles and open sand or fine rubble. They like to sit and watch the world. Leave clear glide paths along the bottom. Keep surfaces smooth to prevent snags during startle runs.

Cycling at 0-2 C takes ages. Do a long, patient fishless cycle with pure ammonia and lots of biomedia. Expect 8-12+ weeks. Seed from an established cold system if you can; warm-water bacteria will not carry the load here.

What to feed them

They are deliberate predators that key on movement. Mine took to tong-fed food after a week of settling in. Offer food right in front of them and give them time to line up the strike.

• Primary: krill (Euphausia), PE mysis, marine amphipods.
• Also accepted: finely cut marine fish, sand lance, squid strips, and prawn pieces.
• Occasional live: coldwater mysids or shore shrimp to start finicky eaters.

Feed small portions 2-3 times per week at 0-2 C. Their metabolism is slow. Thaw frozen foods in chilled saltwater, not warm tap. I soak pieces in a vitamin/iodine mix once a week to round out nutrition. Remove leftovers within 10 minutes; cold systems process waste slowly.

How they behave and who they get along with

Bottom-oriented, calm, and a bit spooky. They sit, then rocket a short distance if startled. Not bullying, not social either. Mine ignored other fishes unless a faster tankmate tried to outcompete at feeding time.

• Best plan: species-only tank.
• Possible companions (if you can source them legally): other slow Antarctic notothenioids of similar size and temperament.
• Avoid: anything tropical or even temperate. At 0-2 C they will not survive. Also avoid hyperactive predators that steal food.

Breeding tips

I have not seen captive breeding, and I do not know anyone who has with this species. In the wild, notothenioids tend to lay large demersal eggs in winter with strong seasonal cues, sometimes with male egg guarding. If you are determined to experiment, set expectations appropriately.

• Run a strong seasonal photoperiod: months of short days, then a gradual spring ramp.
• Keep them lean in winter, feed up slightly in late winter as daylight increases.
• Provide broad flat rocks and sheltered cavities for potential egg sites.
• Maintain near-zero disturbance and ultra-stable temperature through the dark period.

Common problems to watch for

• Temperature creep: rooms warm up, chillers lag. Above 4-5 C for long stretches leads to stress and refusal to feed.
• Ammonia spikes: cold biofilters react slowly. Test often, feed lightly, and change water with pre-chilled, aerated saltwater.
• Oxygen dips: heavy feeding or a skimmer outage can drop O2. Keep redundant aeration in the sump.
• Shipping trauma and anorexia: these fish may go a week or more without eating after transit. Dim the lights and let them settle.
• Infections: small scrapes can fungus at low temps. I isolate and treat in a separate chilled QT with improved flow and very clean water. Go slow with meds; many act differently in cold systems.
• Equipment failure: a dead chiller can end the project. Keep spare pumps, vinyl tubing, and a plan to ice-bath the sump in an emergency.