Napo Cory (Gastrodermus napoensis) – 2.5–4cm Size Grades

Napo Cory (Gastrodermus napoensis) is a small peaceful cory catfish from the upper Amazon basin. The species was long known in the aquarium trade as Corydoras napoensis; the current Eschmeyer Catalog of Fishes accepts Gastrodermus napoensis. Both names are included here so modern taxonomy and older care references connect clearly.

One quantity supplies one unsexed fish in the selected approximate size grade. The current options are 2.5–3cm and 3–4cm. These are dispatch sizes, not adult sizes. Napo Corys are social fish, so a proper same-species group should be part of the buying plan.

Napo Cory at a glance

Group size and aquarium space

Keep at least six Napo Corys together. A group of eight or more is preferable where the aquarium has enough floor space, filtration and feeding area. A single cory may survive, but solitary keeping does not reproduce the social environment this fish is adapted to.

Floor area matters more than height. Around 60 litres is a useful baseline for a small group, while a larger footprint gives more room for open feeding zones and compatible community fish. Plan with the adult group in mind rather than the small dispatch size.

Substrate and layout

Fine aquarium sand is the preferred substrate because it supports normal sifting behaviour and is gentle on the mouth and barbels. Very smooth rounded fine gravel can work, but avoid sharp, coarse or dirty material. Barbel health depends on clean water and bottom hygiene as well as substrate texture.

Use smooth wood, planted or shaded edges and open areas where the group can search for food. Gentle to moderate filtration with good surface movement is suitable. Protect small juveniles from powerful intakes.

Water and maintenance

Keep the aquarium stable at around 22–26°C with pH about 6.0–7.5. Captive stock is adaptable, but abrupt temperature or chemistry changes still cause stress. Ammonia and nitrite should remain at zero in a mature aquarium, with nitrate controlled through appropriate stocking, feeding and regular water changes.

An occasional dash to the surface for an air gulp can be normal for cory catfish. Repeated frantic surfacing by several fish is different and should prompt immediate checks of oxygen, temperature, ammonia, nitrite and filter flow.

Feeding Napo Corys

Napo Corys are not algae-control fish and should not be expected to survive on scraps. Use a complete sinking micro-pellet, soft catfish wafer or another appropriately sized bottom food as the staple. Add suitable frozen or live foods such as daphnia, cyclops, brine shrimp and bloodworm for variety.

Watch a feeding session to confirm that food reaches the whole group. In community tanks, quick mid-water fish can clear food before it reaches the bottom. Spread portions across more than one feeding point when needed.

Tank mates

Choose calm community fish that share the same temperature and water chemistry. Peaceful tetras, rasboras and other non-aggressive upper-water fish can work well. Other cory species may coexist in a larger aquarium, but they do not replace a proper same-species Napo Cory group.

Avoid large predators, aggressive cichlids and boisterous bottom dwellers that repeatedly displace the group. Adult shrimp can often coexist in a peaceful planted aquarium, although tiny shrimplets may be eaten opportunistically.

Breeding

Like other small corys, Napo Corys are egg layers. Condition mature fish on a varied diet and excellent water. Spawning can be encouraged by stable clean conditions and water changes that mimic seasonal cues. Adults may eat eggs, so breeders often move eggs or use a dedicated breeding aquarium.

Fry need very small first foods before moving to newly hatched brine shrimp and fine prepared fry food. Stable water and careful feeding are more important than trying to force rapid growth.

Napo Cory questions

What is the current scientific name?

The current Eschmeyer Catalog of Fishes accepts Gastrodermus napoensis. The former name Corydoras napoensis remains common in aquarium books, shop records and older care material.

How many Napo Corys should I keep?

Keep at least six of the same species. Eight or more is preferable where the aquarium has enough floor space and filtration.

How large do they grow?

Plan for roughly 5–5.5cm as an aquarium adult size. The 2.5–4cm options on this listing are approximate dispatch grades.

What tank size is recommended?

About 60 litres is a practical baseline for a small group, with more floor area preferable for a larger shoal or mixed community.

Do Napo Corys eat algae?

They may investigate edible material on the substrate, but they are not an algae-control species. They need deliberate sinking food and normal aquarium maintenance.

Do they need sand?

Fine aquarium sand is preferred for natural sifting. Very smooth fine gravel can work, but avoid sharp or dirty substrate.

What should I feed them?

Use complete sinking catfish foods as the staple, supported by appropriately sized frozen or live foods such as daphnia, cyclops and brine shrimp.

Can they live with shrimp?

Adults may coexist with aquarium shrimp, but very small shrimplets may be eaten opportunistically.

Why do Napo Corys swim to the surface?

An occasional air gulp can be normal. Repeated frantic surfacing means oxygen, temperature and water quality should be checked promptly.

Can I choose males or females?

No sex is guaranteed by the current size variants.