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Smudge Spot Cory

Scientific Name: Corydoras similis
Family: Callichthyidae, Sub-Family Corydoradinae

About the Smudge Spot Cory

Species Type: Freshwater Fish
Category: Catfish

Care Level: Easy. Does well in a slightly more narrow range of water parameters and shouldn't be used to cycle an aquarium. Will eat most prepared foods. May have some specific care requirements in terms of particular water parameters, social behaviors, food items etc.

Origin: Rio Madeira basin in Rondonia, Brazil. Found in small streams, creeks, pools and flooded forest areas.

Compatibility/Temperament: Very peaceful bottom fish that must be kept in a group of at least three but preferably five or more. Good tank companions for non-aggressive fish like characins, rasbora, dwarf cichlids, angels, gourami, other small catfish.


One of the more distinctively patterned species of Corydoras and therefore a nice addition to a large community tank with other corys. The colouration and intensity can vary somewhat depending upon the fish and its environment; there is a blueish colour to the blotch at the base of the caudal fin and the anterior part of the fish has a beautiful mauve or sometimes golden sheen that can be quite reflective of light. The species name similis is the Latin for "looks like," a reference to the similar colouration and pattern in Corydoras ourastigma, shown in the third photo above; this latter species has a long snout whereas C. similis is rounded.

This species might initially be confused with Corydoras guapore, C. caudimaculatus, C. spectabilis or C. ourastigma which have similar basic patterns, and except for the latter, these all occur in the Madeira/Guapore basin. Only C. similis and C. ourastigma have a "smudged" blotch at the base of the caudal fin rather than a distinct spot as in other spotted-head species.

The aquarium should be well-planted with pieces of bogwood, a dark substrate (small gravel or sand, provided it is smooth-edged) with some open areas, and subdued lighting which can be partly achieved by floating plants; corys do not like bright lighting. Though this species will swim mid-water to browse wood and plant leaves, it spends much of its time foraging the substrate. As with all corys, mature females are rounder when viewed from above.

The Corydoras are quite sensitive to water parameters and quality, and highly intolerant of salt, chemicals and medications. Signs of stress usually begin with rapid respiration, then lethargy (often just "sitting" on plant leaves, wood or the substrate respirating heavily, sometimes near the surface) and sometimes rolling onto one side. At such signs, a partial water change of at least 50% with a good water conditioner should immediately be made, and appropriate steps taken to remove the cause. Any sudden fluctuation in water chemistry or temperature often induces shock, causing the fish to "faint" and fall over on its side. Corydoras introduced to new aquaria will settle in better if the tank is established; Cory's do not adjust well to a new aquarium with still-unstable water conditions and fluctuations.

The dorsal, pectoral and adipose fins are each preceded by a spine which is actually a hardened and modified ray; the pectoral fin spine can be "locked" into position by the fish; care must be taken when netting Cory's not to entangle these spines, which can also give the aquarist a nasty jab. They are believed to be a defense adaptation, to lodge the fish in the throat of a predator.

All species in the genus will periodically and fairly regularly swim quickly to the surface for a gulp of air. The fish swallows the air and blood vessels in the hind gut extract oxygen from the air; it is then expelled through the vent the next time the fish breaks the surface for another gulp of air. This adaptation is believed to have evolved so that the fish can survive in poorly-oxygenated water such as drying pools during the dry season. It is however essential to the fish's well-being that it regularly swallows air.

The genus name is derived from the Greek "Cory" meaning helmet, and "doras" meaning skin, incorrectly used here for "armour"; it refers to the dual row of overlapping plates (instead of scales) along the body, comparable to a suit of armour. This species was described by H. Hieronimus in 1991.

Smudge Spot Cory Diet

In its habitat it feeds on worms, small crustaceans and insect larvae; in the aquarium it readily accepts prepared sinking foods like tablets and pellets, frozen bloodworms and live worms.


May attain 2.4 inches but usually around 2 inches.

Minimum Tank Suggestion

24 inches in length.

Ideal water parameters for Smudge Spot Cory

Soft (hardness below 15 dGH) acidic (pH below 7.0) water, temperature 21-27C/70-81F.

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Smudge Spot Cory 1
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Smudge Spot Cory 2
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Smudge Spot Cory 3

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