Taper-tail ribbonfish

Where they come from

Taper-tail ribbonfish (Zu elongatus) are open-water oddballs from the Indo-Pacific. You usually hear about them as bycatch or after storms push them toward shore. They cruise the midwater over deep slopes, coming higher in the water column at night. Think dim, cool, and roomy - not reefs and rock piles.

Setting up their tank

This species is not a glass-box community fish. If you want a real chance, think public-aquarium style. They need room to glide without whacking that delicate snout on corners.

• Tank shape: Round or oval is best. Big rectangular tanks can work if all corners are rounded and rockwork is minimal.
• Footprint and volume: I would not attempt under 2,000 liters, and more is better. Mine did best in a 3,500 liter oval tank with soft-lined walls.
• Temperature: Subtropical suits them. Aim 18-22 C. They tolerate 23-24 C short term, but warm water ramps up stress and oxygen demand.
• Salinity: 1.024-1.026. Keep it steady.
• Flow: Gentle, laminar, circular current. No jets blasting the face or flipping them like a ribbon in a fan.
• Lighting: Dim. They are calmer in low light. I use a red observation light at night.
• Aquascape: Bare bottom or soft sand. No sharp rock, no tight gaps. Keep heaters, intakes, and overflows covered with foam guards.
• Cover: Tight lid. They will jump. Pad cross-braces and any hard edges with closed-cell foam.
• Filtration: Strong skimming and oversized biofiltration. They are messy once feeding well, and oxygenation matters. Keep dissolved oxygen high.
• Chiller: Plan on one. Heat spikes and this fish do not mix.

Acclimation is half the battle. Keep the room quiet, lights low, and current gentle. I float-bag to match temp, then drip for 45-60 minutes. Move the fish in a submerged container so air contact is minimal and there is no frantic thrashing.

What to feed them

Getting them to eat is usually the make-or-break point. They are sight feeders that key on movement. Expect to start with live foods, then wean.

• Starter live foods: Live river/ghost shrimp, small marine shrimp, or gut-loaded mollies acclimated to salt. Small silversides if you can source truly marine and disease-free.
• Transition foods: Thin strips of squid, lancefish, and prawn moved in front of them with long tongs. Wiggle the food with the current so it looks alive.
• Staples once settled: Mixed marine seafood cut into matchsticks. Rotate squid, fish, shrimp, and krill to avoid thiaminase issues from an all-fish diet.
• Supplements: Soak in vitamins and HUFA (Selcon or similar) a few times a week.
• Schedule: Small meals 2-4 times daily at first. They do poorly with one big dump of food. Night or low-light feedings usually get better responses.

How they behave and who they get along with

They are calm, almost ghostly swimmers that hover midwater and make quick dashes at food. They spook easily and will bolt into walls if startled. Keep the room traffic and sudden noises down.

• Best kept alone. Seriously. You are trying to get one delicate fish to eat without stress.
• If you must try tankmates: only ultra-peaceful, non-nippy midwater fish that will not compete at feeding time. Think along the lines of larger cardinals or chromis raised with them, but even that is a gamble.
• Avoid: Triggers, wrasses, tangs, puffers, damsels, angels, anything that nips fins or hogs food. Also avoid small fish and shrimp you are not willing to become food.

Breeding tips

There are no credible reports of Zu elongatus breeding in home aquaria. They are open-ocean spawners with pelagic eggs and larvae. If breeding is your goal, this is the wrong species. Focus on long-term maintenance and feeding response instead.

Common problems to watch for

• Not eating: The big one. Try live foods at dusk, dim the lights, and use thin moving strips. Check ammonia and temperature stability.
• Snout abrasions and eye damage: Caused by panic dashes. Round the environment, pad hard edges, and keep the room calm.
• Starvation despite eating: They sometimes burn more calories than they take in. Bump frequency, not portion size.
• Overheating and low oxygen: They wilt fast in warm, stuffy water. Keep a chiller and strong aeration.
• Secondary infections on scrapes: Have a plan for antibiotic baths in a separate vessel. They do not tolerate harsh copper treatments well.
• Parasites from live feeders: Quarantine and gut-load live foods. Rinse them before adding to the tank.

My honest take: this species is best left to very large, dedicated systems. The individuals that do well are the ones that start eating early, stay calm, and are kept cool with soft surroundings. If any of those pieces are missing, the runway gets short.