Guppy conger

Where they come from

The Guppy conger is a deep-slope conger eel from the Caribbean and the tropical western Atlantic, named after Trinidadian naturalist Robert Guppy. You usually see them trawled from muddy or silty bottoms, well below the bright reef zone. That background explains a lot of their quirks in aquariums: they like dim light, coolish tropical temps, and a place to dig in.

Setting up their tank

Plan big. A full-grown Guppy conger gets long and thick, and it moves like a snake through sand. I would not attempt one without a tank in the 300+ gallon range with a wide footprint (8x3 ft is lovely). A juvenile can start in something like a 180, but that is a stopgap.

• Substrate: 2-4 inches of fine sand so it can burrow. Skip sharp rubble.
• Hides: PVC pipe sections (2-3 inch diameter) partly buried in sand. Cap the back with a rock so it feels like a den.
• Rockwork: Put base rocks directly on the glass/stand, then add sand. You do not want a burrow causing a rockslide.
• Lighting: Keep it dim or give lots of shaded zones. They are deepwater and light-shy.
• Flow and gas exchange: Moderate flow with vigorous surface agitation. Big skimmer helps a lot.
• Lid: Escape-proof the tank. Every gap gets covered or taped. Weight the lids.

Parameters that worked for me: 1.023-1.026 specific gravity, pH 8.0-8.3, temp on the cooler side of tropical. I kept mine at 72-74 F (22-23 C) and it stayed calm and fed well.

Acclimation: Dim the room, use a drip line, and avoid nets. Guide the eel in a smooth container or PVC tube so you do not scrape its skin. Let it settle with lights low for a day or two before you try to feed.

What to feed them

Think meaty and marine-based. They are ambush predators that grab prey from the burrow entrance.

• Good staples: pieces of fresh or frozen marine fish, squid, prawn/shrimp, scallop, clam.
• Training: Use long feeding tongs. Wiggle the food just outside the burrow. They cue on movement.
• Schedule: Once settled, 2-3 targeted feeds per week is plenty for adults. Juveniles can take smaller meals more often.
• Supplements: Rotate foods and add a vitamin/HUFA soak once or twice a week.

How they behave and who they get along with

They spend a lot of time with just the head poking out. Mostly twilight and nighttime movement. Early on they act reclusive, then get bolder once they figure out you are the food source.

• Tankmates: Keep it simple. Large, calm fishes that do not nip are your best bet.
• Avoid: Triggers, big wrasses, puffers, and anything that picks at fins or tails. Those fish harass eels.
• Also avoid: Small fish or crustaceans you care about. If it fits, it is food, especially at night.
• One per tank: They are not social, and similar eels will compete for the same burrow.

Breeding tips

Nothing practical for home aquariums. Like other congers, they spawn in the open ocean and have a long leptocephalus larval stage. No confirmed home breeding reports, and sexing adults is not straightforward. Focus on giving it a safe, quiet burrowed life instead.

Common problems to watch for

• Refusing food: Normal the first week. Keep lights low, try squid or prawn on tongs, and leave the room after offering. Consistency wins.
• Scrapes and mouth injuries: Usually from rough rock or nets. Use smooth PVC hides and gentle handling.
• Jumping/escaping: Any sudden noise or bright light can trigger it. That is why we obsess about lids.
• Water quality swings: Big predators load the biofilter. Oversize your skimmer and keep nitrate under control with water changes and good export.
• Medication sensitivity: Eels do poorly with copper. For parasites, consider a separate hospital tank and eel-safe approaches (formalin dips under guidance, tank transfer, or carefully dosed chloroquine if you know what you are doing).
• Nutritional gaps: Rotate foods and add vitamins. A single-item diet shows up as poor appetite and body condition over time.