Post by MADMIKE on Oct 19, 2006 8:24:56 GMT -5
Corydoras
Dwarfs and Pygmies
To follow on from my previous article ‘From small beginnings’ I thought is would be a good idea to introduce some more of the smaller species of Corydoras, these are affectionately known as ‘Dwarf’ or ‘Pygmy’ Cory’s. There are six species in all that I would put into this group. These are Corydoras cochui Myers & Weitzman, 1954; Corydoras gracilis Nijssen & Isbrücker, 1976; Corydoras habrosus Weitzman, 1960; Corydoras hastatus Eigenmann & Eigenmann, 1888; Corydoras pygmaeus Knaack, 1966; and Corydoras xinguensis Nijssen, 1972. All six species grow no larger than one and a half inches standard length (Tip of snout to caudal peduncle). In the majority of all Corydoras species it is the females that grow to the largest size, and in many instances the males are noticeably smaller.
The availability of these ‘Dwarf’ species varies depending on the time of year, Corydoras habrosus, Corydoras hastatus and Corydoras pygmaeus can usually be obtained all year round. Corydoras cochui and Corydoras xinguensis on the other hand are only occasionally imported, Corydoras gracilis is extremely rare in the hobby and on the rare occasions that they are imported they demand very high prices. In twenty-five years of keeping Corydoras I have only seen one live specimen.
Other than Corydoras gracilis, the other five species are relatively easy to keep and maintain. They do not require large tanks; a standard 24?x 12?x 12? is more than big enough to house a group of a dozen of any of the first four species. A substrate of smooth sand, a piece of bogwood, a couple of clumps of Java fern and a portion of Java moss. For this size of tank I prefer to use internal or external power filtration, because of the size of the substrate an under gravel filter would soon become clogged and stop functioning.
Corydoras cochui, are a purely bottom dwelling species that rarely moves away from the substrate, this is indicated by its swimming motion. The only time I have seen these fish move away from the bottom is when they are spawning; the females swim up into the fronds of the Java moss, or up the corners of the tank to deposit their eggs. Corydoras habrosus, Corydoras pygmaeus and Corydoras xinguensis are species that do venture into up into the upper water levels both in their search for food and when spawning. The odd one out is Corydoras hastatus; this is a species that is unique in the Corydoras world in as much as it prefers to swim freely in all areas of the tank and particularly in the company of other small fish. In their natural habitat they are often found swimming with the small tetra Odontostilbe kriegi that has an almost identical colour pattern. Shoaling fish such as small Tetras or Rasbora’s make ideal tank mates for any of these catfish; I had a group of six Corydoras hastatus that swam around happily with a shoal of twenty hengeli Rasbora’s.
Breeding any of the five species is not in its self very difficult; for this I use relatively small tanks that were purpose built for the job. However a standard 10?x 8?x 8? tank would be ideal, a water temperature of seventy to seventy five degrees Fahrenheit (21º-25ºC) is ideal, the chemistry is not that important so long as it is not to extreme, a thin layer of smooth sand on the bottom, a sponge filter at one end and a large clump of Java moss makes just the right set up. Six fish, four males and two females make up the breeding stock; although breeding from pairs is OK I find I get better results from small groups. A feeding regime that includes live foods at least once a week would soon bring the fish into breeding condition. Thirty percent weekly water changes are also a must to keep the whole environment in first class condition. It will not be difficult to see when the fish are in breeding condition because the females will have filled out and be plump looking, the trick now is to trigger them into spawning mode. Nine times out of ten the weekly water change will set them off, however the first spawning of a group often needs a little kick start, this I usually do by giving the fish a fifty percent water change, only this time I will use water that is about ten degrees Fahrenheit cooler (5.5ºC). In most cases spawning activity will start within twenty-four hours, of the water temperature returning to its original setting. These five species will deposit their eggs on all areas of the tank sides, especially favouring the silicon in the corners, the Java moss will also be given its fair share of eggs.
With the exception of Corydoras habrosus and Corydoras xinguensis, I will leave the adult fish with the eggs; I have found that if given plenty of cover in the form of a large amount of Java moss most of the eggs and emerging fry are left alone. In the case of Corydoras habrosus and Corydoras xinguensis I will remove the adult fish as soon as they have finished spawning. The eggs usually take three and a half to four and a half days to hatch, the fry then take a further two days to absorb the yoke sack and become free swimming. At the end of the second day after hatching I will start to introduce a little food, which will be in the form of microworm, after three days feeding microworm I will start to introduce small amounts of pre-soaked powdered flake food, followed with alternate feeds of newly hatched brine shrimp. From the time the fry have become free swimming I also start to make small daily water changes to ensure the best possible conditions for the growing fry are maintained. With the species where I leave the adult fish with the eggs after spawning, being small fish the feeding pattern does not have to alter, that is to say that the fry and adults receive the same food. The general regime is slightly different in that the water is partially changed twice weekly, with a larger cooler change being made every fifth or sixth week. Before the cool water change is made I will with the aid of a piece of small diameter silicon tube, siphon out most of the small fry and put them into a larger tank for growing on.
In the case of Corydoras hastatus and Corydoras pygmaeus growth is fairly rapid, with fry reaching maturity and themselves breeding within six months.
Ian Fuller
Dwarfs and Pygmies
To follow on from my previous article ‘From small beginnings’ I thought is would be a good idea to introduce some more of the smaller species of Corydoras, these are affectionately known as ‘Dwarf’ or ‘Pygmy’ Cory’s. There are six species in all that I would put into this group. These are Corydoras cochui Myers & Weitzman, 1954; Corydoras gracilis Nijssen & Isbrücker, 1976; Corydoras habrosus Weitzman, 1960; Corydoras hastatus Eigenmann & Eigenmann, 1888; Corydoras pygmaeus Knaack, 1966; and Corydoras xinguensis Nijssen, 1972. All six species grow no larger than one and a half inches standard length (Tip of snout to caudal peduncle). In the majority of all Corydoras species it is the females that grow to the largest size, and in many instances the males are noticeably smaller.
The availability of these ‘Dwarf’ species varies depending on the time of year, Corydoras habrosus, Corydoras hastatus and Corydoras pygmaeus can usually be obtained all year round. Corydoras cochui and Corydoras xinguensis on the other hand are only occasionally imported, Corydoras gracilis is extremely rare in the hobby and on the rare occasions that they are imported they demand very high prices. In twenty-five years of keeping Corydoras I have only seen one live specimen.
Other than Corydoras gracilis, the other five species are relatively easy to keep and maintain. They do not require large tanks; a standard 24?x 12?x 12? is more than big enough to house a group of a dozen of any of the first four species. A substrate of smooth sand, a piece of bogwood, a couple of clumps of Java fern and a portion of Java moss. For this size of tank I prefer to use internal or external power filtration, because of the size of the substrate an under gravel filter would soon become clogged and stop functioning.
Corydoras cochui, are a purely bottom dwelling species that rarely moves away from the substrate, this is indicated by its swimming motion. The only time I have seen these fish move away from the bottom is when they are spawning; the females swim up into the fronds of the Java moss, or up the corners of the tank to deposit their eggs. Corydoras habrosus, Corydoras pygmaeus and Corydoras xinguensis are species that do venture into up into the upper water levels both in their search for food and when spawning. The odd one out is Corydoras hastatus; this is a species that is unique in the Corydoras world in as much as it prefers to swim freely in all areas of the tank and particularly in the company of other small fish. In their natural habitat they are often found swimming with the small tetra Odontostilbe kriegi that has an almost identical colour pattern. Shoaling fish such as small Tetras or Rasbora’s make ideal tank mates for any of these catfish; I had a group of six Corydoras hastatus that swam around happily with a shoal of twenty hengeli Rasbora’s.
Breeding any of the five species is not in its self very difficult; for this I use relatively small tanks that were purpose built for the job. However a standard 10?x 8?x 8? tank would be ideal, a water temperature of seventy to seventy five degrees Fahrenheit (21º-25ºC) is ideal, the chemistry is not that important so long as it is not to extreme, a thin layer of smooth sand on the bottom, a sponge filter at one end and a large clump of Java moss makes just the right set up. Six fish, four males and two females make up the breeding stock; although breeding from pairs is OK I find I get better results from small groups. A feeding regime that includes live foods at least once a week would soon bring the fish into breeding condition. Thirty percent weekly water changes are also a must to keep the whole environment in first class condition. It will not be difficult to see when the fish are in breeding condition because the females will have filled out and be plump looking, the trick now is to trigger them into spawning mode. Nine times out of ten the weekly water change will set them off, however the first spawning of a group often needs a little kick start, this I usually do by giving the fish a fifty percent water change, only this time I will use water that is about ten degrees Fahrenheit cooler (5.5ºC). In most cases spawning activity will start within twenty-four hours, of the water temperature returning to its original setting. These five species will deposit their eggs on all areas of the tank sides, especially favouring the silicon in the corners, the Java moss will also be given its fair share of eggs.
With the exception of Corydoras habrosus and Corydoras xinguensis, I will leave the adult fish with the eggs; I have found that if given plenty of cover in the form of a large amount of Java moss most of the eggs and emerging fry are left alone. In the case of Corydoras habrosus and Corydoras xinguensis I will remove the adult fish as soon as they have finished spawning. The eggs usually take three and a half to four and a half days to hatch, the fry then take a further two days to absorb the yoke sack and become free swimming. At the end of the second day after hatching I will start to introduce a little food, which will be in the form of microworm, after three days feeding microworm I will start to introduce small amounts of pre-soaked powdered flake food, followed with alternate feeds of newly hatched brine shrimp. From the time the fry have become free swimming I also start to make small daily water changes to ensure the best possible conditions for the growing fry are maintained. With the species where I leave the adult fish with the eggs after spawning, being small fish the feeding pattern does not have to alter, that is to say that the fry and adults receive the same food. The general regime is slightly different in that the water is partially changed twice weekly, with a larger cooler change being made every fifth or sixth week. Before the cool water change is made I will with the aid of a piece of small diameter silicon tube, siphon out most of the small fry and put them into a larger tank for growing on.
In the case of Corydoras hastatus and Corydoras pygmaeus growth is fairly rapid, with fry reaching maturity and themselves breeding within six months.
Ian Fuller