Fly River garfish

Where they come from

Fly River garfish (Zenarchopterus novaeguineae) come out of New Guinea, especially the Fly River system and nearby lowland waters. Think warm, soft-to-medium water, lots of cover along the edges, and a surface full of insects. They are built for cruising the top layer all day.

Setting up their tank

Give them length more than height. These fish are basically surface torpedoes, and they use that top 2-3 inches constantly. A long tank with open swimming room up top and structure along the sides works way better than a tall show tank.

• Tank size: I would not bother under 4 ft long for a group. Bigger is calmer.
• Lid: tight-fitting, no gaps around pipes. They jump hard and fast.
• Filtration: strong but not a washing machine at the surface. Aim flow along the back or use spray bars.
• Surface: floating plants or a strip of cover helps them feel less exposed.
• Lighting: not too brutal. Bright lights with no shade makes them skittish.

I like to set the tank up with hardscape and plants pushed to the sides, leaving a clear "runway" down the middle. Floating plants (or even a band of water lettuce) makes a huge difference in how confident they act.

Water-wise, stability beats chasing numbers. Warm temps, clean water, and steady maintenance matter more than obsessing over a specific pH. That said, they do best in the usual New Guinea river range: neutral-ish, not ice cold, and not rock-hard liquid stone.

What to feed them

They are surface predators with small-ish mouths. Mine mostly wanted moving food in the top layer, and they can be picky at first. If you buy skinny imports, expect a "training" phase.

• Best starters: live or frozen mosquitoes, bloodworms, daphnia, brine shrimp, chopped blackworms
• Once settled: small floating pellets, floating micro-sticks, insect-based foods
• Treats: small crickets/flightless fruit flies (careful with size), chopped shrimp, finely cut fish flesh occasionally

If they ignore pellets, mix pellets in with frozen, or pre-soak pellets in thawed food juice and offer right at the surface flow. A confident "first eater" in the group teaches the rest.

How they behave and who they get along with

They are alert, fast, and surface-focused. In a group they settle in and act more natural, but you will still see quick darts and occasional sparring. Most of the drama is about pecking order and food at the surface.

• Best kept: in a group, in a long tank with lots of surface room
• Temperament: not a bully in the usual sense, but will outcompete slow surface fish at feeding time
• Activity zone: top layer, especially the first few inches

Tankmates should be peaceful and able to handle fast surface feeders. Midwater schooling fish that are quick (and not fin-nippy) tend to work. Bottom fish are usually ignored, which is nice.

Also skip notorious fin nippers. A stressed garfish that gets harassed at the surface turns into a glass-surfing jumper. Calm tankmates keep them in the tank.

Breeding tips

Breeding Zenarchopterus in home tanks is possible but not something you just stumble into like guppies. In the hobby you will usually run into two hurdles: getting a comfortable, mature group, and getting fry through the early days without them vanishing.

• Start with: a decent-sized group so you likely get both sexes
• Give them: heavy feeding (insecty foods) and warm, stable water
• Provide: floating plants and quiet surface areas for courtship and hiding fry

If you do get young, the adults may snack on them. I would move fry to a grow-out or use a thick mat of floating plants so some can dodge the adults. Newly born/very small young do well on baby brine shrimp and powdered foods that stay near the surface.

Common problems to watch for

• Jumping: the number one killer. Seal the lid and keep water level a bit lower if needed.
• Shipping damage and skinny imports: they can come in beat up, with mouth wear or fin damage. Clean water and easy foods help them recover.
• Refusing food: common early on. Start with live/frozen, then convert slowly.
• Surface stress: too much surface turbulence or bright, uncovered lighting makes them nervous and flighty.
• Mouth injuries: they can smack lids or hardscape during spooks. Keep the top area clear and use floating plants as a "soft ceiling."
• Internal parasites: if they keep eating but never gain weight, consider a quarantine and deworming plan.

If you can get them eating confidently and you treat the tank like a "surface fish" setup (lid, cover, long swim space), they are incredibly fun. Watching a healthy group patrol the top like little river needles never gets old.