Manglolo

Where they come from

Sicydium bustamantei is a river goby from fast, clear streams in Central America. Think rock gardens, whitewater, and bright sun. They use a pelvic suction cup to cling to boulders while they rasp algae. Like many sicydiine gobies, they are amphidromous: adults live and spawn in freshwater, but the hatchlings drift to the sea, grow for a while, then the youngsters ride the currents back up into the rivers.

Setting up their tank

Set this species up like a river, not a pond. Current and oxygen are the whole game. A mature, algae-rich hardscape matters more than decorations.

• Tank size: 30 inches length or more for a small group. More footprint beats height.
• Flow: 15-30x turnover with directional powerheads or a river-manifold. Aim for a strong, laminar push across rock faces.
• Temperature: 70-76 F (21-24 C). They handle cooler nights fine. Avoid long stretches above 78 F.
• Water: very clean, well-oxygenated. pH 6.8-7.8, moderate hardness. Big, regular water changes.
• Substrate: sand or fine gravel with piles of rounded river stones and cobbles. They spend their day on rock faces.
• Light: bright. You want healthy biofilm growth on the rocks.

Let the tank run for a few months with high light and flow. If the only algae you see is long hair algae, the biofilm is not mature yet. These gobies want thin, soft films and diatoms, not stringy mats.

What to feed them

They are specialized grazers. Mine spend hours rasping microalgae and diatoms off smooth rock. Sinking pellets are a bonus, not the main course.

• Primary: natural biofilm on rocks and wood.
• Staples to add: nori sheets rubber-banded to stones, spirulina flakes pressed onto rock faces, algae wafers shaved thin and stuck to surfaces.
• Great trick: paint Repashy Soilent Green or Super Green onto warm rocks, let it set, then drop them in.
• Occasional: frozen cyclops or baby brine. Go easy on protein-heavy foods to avoid bloat.

How they behave and who they get along with

Expect a lot of perching and rock-hopping. Males stake out a favorite stone in the current and posture at rivals, but scuffles are short. They mostly ignore midwater fish.

• Best kept as 1 male with 2-3 females, or multiple males only if the tank has long rock lines and broken sightlines.
• Good tankmates: river fish that like current and cool, clean water. Danios, white clouds, smaller rainbow shiners, hillstream loaches, and Amano shrimp all work well.
• Avoid: big cichlids, barbs that nip, plecos and Siamese algae eaters that bulldoze the rocks and outcompete them for algae.

Breeding tips

You may see courtship and egg guarding under a stone in strong flow, but raising the young is the hard part. The larvae need a marine phase. In a home tank they hatch, drift, and vanish into filters.

• If you are curious: provide flat stones in high flow and keep the water very clean. Males will clean a spot and fan eggs.
• Raising larvae requires moving them to saltwater, feeding rotifers under strong light, and weeks of careful rearing. I have not pulled this off, and I do not know hobbyists who have done it with this exact species.

Common problems to watch for

• Starvation in new tanks: they look fine for weeks, then fade. If there is not steady biofilm, they are not eating enough.
• Low oxygen: panting on the glass or hanging at the surface means bump up flow and aeration immediately.
• Overheating: sustained temps in the high 70s F lead to wasted fish and infections. Use a fan or chiller in summer.
• Bloat from rich foods: heavy protein pellets can cause trouble. Keep the diet algae-heavy.
• Scrapes and fungus: they slam rocks in current. Use smooth stones and keep water pristine so small wounds heal.
• Jumping and climbing: cover every gap. They will go up airlines and heater cords.
• Medication sensitivity: go gentle. Half-dose formalin-malachite or use salt and extra oxygen. Copper is risky for gobies.