Short-tail eel catfish

Where they come from

Short-tail eel catfish (Plotosus abbreviatus) are a marine catfish from the Indo-West Pacific. You will see them tied to reefs, rubble zones, and sandy areas near structure. Juveniles are famous for schooling (sometimes in tight balls), and as they get bigger they tend to spread out and get more independent.

They are not a "cute oddball" for long. They put on size, they get confident, and they come with real hardware (venomous spines). That combo is why I call them an advanced fish even if they eat like a pig.

Setting up their tank

Think "messy, strong, and roomy." These catfish eat heavy, poop heavy, and cruise the bottom. A small tank works for a short time and then suddenly does not.

• Tank size: I would not start one in anything under 180 gallons, and bigger is better if you want it long term.
• Filtration: oversize your skimmer and mechanical filtration. Socks/roller mats help a lot because they kick up sand and leave chunky waste.
• Flow: moderate to strong, but give them calmer pockets behind rockwork so they can rest.
• Aquascape: stable rock on the glass (or on a PVC/eggcrate base), then sand around it. They will dig and shove.
• Lid: tight fitting. They are not classic jumpers, but a spooked eel-shaped fish can find openings.
• Lighting: whatever you like for the tank. They do not care, but they appreciate shaded areas.

Sand is fine, and they look natural on it, but pick a grain that will not turn into a sandstorm in high flow. Medium aragonite tends to behave better than super-fine sugar sand with these guys.

Plan your maintenance routine before the fish goes in. With Plotosus, you will feel it fast if you skip water changes or let detritus pile up in dead spots.

What to feed them

They are enthusiastic eaters. The trick is not getting them to eat, it is keeping the diet clean and not turning the tank into a nutrient swamp.

• Staples: shrimp, squid, clam, mussel, fish fillet, and quality sinking marine carnivore pellets.
• Good rotation: mix in different seafoods so you are not just feeding one thing forever.
• How often: smaller individuals do well with smaller daily feedings. Adults I feed 3-5 times a week, generous but not sloppy.
• Soaking: occasional vitamin and HUFA (like Selco-style) soaks help if you are feeding lots of frozen.
• Avoid: feeder fish, freshwater beef heart type foods, and super oily low-grade seafood. They foul water fast and do the fish no favors.

Watch the belly line. A well-fed fish looks solid but not ballooned. If it is getting thick behind the head and you are fighting nitrates all the time, you are probably feeding like it is a grouper.

How they behave and who they get along with

Juveniles can school and look "peaceful," but they are still predators. Anything that fits in their mouth is on the menu, and they get bold at night. They are also very food-driven, so they barge in at feeding time.

• Temperament: generally not a fin-nipper, but will eat small fish and crustaceans.
• Activity: more active at dusk/night, but in captive tanks they learn your schedule and will cruise out for food.
• Reef safety: not reef-safe with shrimp/crabs, and they can topple loose frags or rock while bulldozing.
• Best tankmates: sturdy medium-to-large fish that can handle a pushy eater (larger tangs, angels, rabbitfish, triggers that are not overly aggressive, some wrasses).
• Avoid: tiny fish, ornamental shrimp, small crabs, delicate slow feeders, and anything that will harass it constantly.

One more behavior note: they wedge themselves into tight spaces. Make caves and tunnels big enough that the fish can turn around. If they have to reverse out of everything, you will see more scrapes and stress.

Breeding tips

Breeding them in home aquariums is basically a non-event. Plotosus species have more complex reproductive behavior than most hobby setups can support, and you would need a lot of space and the right social grouping. I would treat them as a display/pet fish rather than a breeding project.

If you ever do see courtship-like behavior (increased following, circling, more daytime activity), take it as a cue to keep the water extra clean and keep your hands out of the tank as much as possible. Stress tends to shut the whole thing down.

Common problems to watch for

Most issues I have seen with these come from three places: too small a tank, dirty water from heavy feeding, and injuries from rockwork or bad handling.

• Nitrate/phosphate creep: heavy feeding plus heavy waste. Fix with better export (skimmer, water changes, mechanical filtration) and less messy feeding.
• Scrapes and barbel damage: usually from sharp rock, squeezing into tight crevices, or abrasive substrate.
• Marine ich/velvet: they are not magically immune. Quarantine is worth it, but be careful with meds and oxygen levels in QT.
• Secondary infections: a small scrape can turn into a bacterial mess in warm, dirty water.
• Ammonia spikes after big meals: uneaten chunks rot fast. Siphon leftovers and clean socks/rollers frequently.

If you keep up with export, give them elbow room, and respect the spines, they are hardy and personable. But they will absolutely punish sloppy maintenance, so set the system up like you mean it.