Hot Water Fish


  • Scientific name:  Corydoras
  • Common Name:  Cleaner Fish, Garbage Fish
  • Aquarium size:  60 to 80 liters
  • Temperament: Calm, sociable and gregarious
  • Temperature:  Between 22º and 27ºC
  • pH: Between 6 and 8
  • Diet:  Omnivore and detritivores
  • Length:  3 cms to 6 cms



Corydoras belong to the freshwater siluriform actinopterygium genus. Other varieties of fish have evolved a lot, but the Corydoras not so much, they are original fish of the Paleocene epoch , being very resistant and good at adapting to waters with little oxygen.
They are very well suited to community aquariums, since they occupy the lower part, where they do not compete for space with other species.
In the aquarium they carry out an important maintenance and cleaning function, since they consume food remains that settle to the bottom and although one of their terms of reference is «aquarium pool cleaner» or «garbage fish» it should be clarified that this specimen does not consume excrement of other fish.
I would highlight that if you intend to have Corydoras in your aquarium, they are gregarious fish that need a small school of at least 5 to 6 individuals, so that they are active and do not contract any disease caused by stress.


This species of fish has a flattened ventral part and a convex dorsal part.
The body and head are compressed and the eyes are more or less superior. They have a small adipose fin that lies behind the dorsal fin and is characteristic of the callichthyidae family.
The pectoral fins formed by a large spine are important for their reproduction.
They do not have scales, instead, they have two rows of bony plates along the body that overlap it, covering the flanks, back and head.
In fact, its name «Corydoras» originates from the Greek words Kóry (helmet) and doras (skin).
Another characteristic detail is the pair ofbeards or mustaches located on the lower jaw with great sensory capacity to help them search for food at the bottom of rivers and lakes.
Its mouth is positioned downwards to be able to eat the food from the sand.
They use the swim bladder to breathe atmospheric air, which is then processed by the stomach and expelled as gases through the anus. That is why they can be observed on some occasions coming to the surface to ventilate, but if this is very recurrent it is also a sign that there is very little oxygen in the aquarium.
They can move through places where there is almost no water as long as the degree of humidity at the bottom is high.
Its size depends on the species. In aquariums it varies from 3 to 6 centimeters but in their wild habitat they can measure up to 14 centimeters.
They are very little hydrodynamic or poor swimmers, so they prefer clean waters with slow currents and a sandy bottom, to facilitate their movement in search of food.

Sexual dimorphism

The differences between males and females are very difficult to find with the naked eye.
Almost always the female is larger than the male and her belly is bulky, being noticed more frequently when she is an adult or is in the reproductive period.

Corydora fish coloring

Its coloration is gray, with metallic spots of violet, green, yellow, black and blue, being observed in some species stripes with wavy shapes, which are distributed on the head and the upper part of the back, also forming horizontal lines on the sides.

Varieties of Corydoras

The most common varieties of Corydoras in aquariums are:

  • Corydoras Paleatus
  • Melini
  • Sterbai
  • Pepper
  • Pygmy
  • Adolfi
  • Arcuatus
  • Barbatus
  • Melanistius
  • Metae
  • Dubius
  • Julii

Distribution and habitat

Its distribution is very wide. They are found endemically in almost all the countries of South America and part of Central America.
Most of the species come from the tributaries of the Amazon River, Orinoco, rivers of the coasts of Guyana and Suriname. In short, it can be said that they extend from Argentina to the extreme north of Venezuela.
Its habitat is represented by shallow tropical fresh water, although its adaptability is so great that it ranges from the most tropical climates to the coldest, reaching species of these fish in the Patagonian region.
They normally travel long distances in shoals, foraging for food at the bottom of lakes, rivers, estuaries, and swamps.
The proper temperature for living depends on the origin of the species. The ranges go from 16 ° C that the Corydoras from the south of La Plata in Argentina support, to over 28 ° C that other Amazonian species support.

Aquarium conditions

In the aquarium, this cleaner fish must have an aquarium of a minimum size of 70 liters for a school of Corydoras pygmaeus (Dwarf catfish). Now, if you choose a Corydoras barbatus, the aquarium should be about 150 to 200 liters, which would hold a group of 4 to 6 specimens. A special 60-80 liter aquarium without a bottom filter is recommended for the young. For the cleaner fish to adapt to the environment of the aquarium, it must have a sandy or soft gravel bottom with branches, trunks and natural plants according to the lighting , nutrients and substrates of the environment. Oversized filtration must be used

to keep nitrogenous compounds under control, and especially ammonia, which does a lot of damage to them.
These fish are not recommended for densely planted aquariums since, since they are shoal-dwelling, very active and live at the bottom looking for food, they may eventually dig up the plants.
The quality of the water for an aquarium with Corydoras must be kept within very specific parameters:

  • pH: Between 6.2 and 7.4
  • gH: Between 10º and 14º
  • Temperature: Between 23ºC and 26ºC

Filter types, brands and filter materials

  • Best backpack filter for aquarium
  • Best internal filter for aquarium
  • Best external filter for aquarium
  • Best Fluval filters 
  • Best Eheim filters
  • Best AquaClear filters
  • Best Hydra filters
  • Best perlon 
  • Best Activated Carbon for Aquarium Filters


Their diet requires a high protein intake. They can be fed brine shrimp, mosquito larvae, tubifex, grindal, plant food such as spirulina, homemade porridge, boiled vegetables and daphnia.
There are many foods specially prepared for ground fish , which will perfectly help you to maintain a balanced diet, placing one tablet for every 3 or four fish. Frozen food can also be buried in them.

Everything you need to maintain your aquarium

  • Best digital pH meter
  • Best Aquarium Test
  • Best anti-algae
  • Best bacteria for aquarium
  • Best siphoner for aquarium
  • Best Aquarium Water Clarifiers
  • Best reverse osmosis filters for aquarium
  • Best UV lamps for aquariums

Behavior and compatibility

As it is a bottom fish, its behavior is calm and sociable , being able to interact with other peaceful fish.
They are ideal for community aquariums since they share the spaces with not very large fish, preferably from the family of cyprinids , characins and other peaceful catfish. The group of panda Corydoras are the most active and sociable.

Corydoras compatible fish

Compatible fish without restrictions

  • Tiger Barbel
  • Scalars, Angelfish
  • Guppy
  • Neon Tetra
  • Silver dollar
  • Rasbora Galaxy
  • Kribensis
  • Betta fish 
  • Platy
  • Ancistrus

Compatible fish without restrictions

  • Boraras
  • Cherry barbel
  • Harlequin
  • Botia Clown
  • Drunk
  • Corydora
  • Little nun
  • Ax fish
  • Telescope
  • Disk

Compatible fish without restrictions

  • Gourami Pearl
  • Chinese neon
  • Snail Apple
  • Zebra fish
  • Ramirezi

Restricted Compatible Fish

  • Koi carp
  • Oscar

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