Raising and Breeding Corydoras Gossei

Currently there are approximately 180 species of Corydoras that are classified with more and more species being classified all of the time, included in the recent species are the Corydoras Glossei. They first became available in the early 1970's and proved to be popular straight away with many new keepers of these fish quickly setting up breeding projects.

These fish have a small natural locality, they are endemic to the tributaries of the Rio Mamore which is situated in Brazil, their small natural waters probably accounts for their late discovery and classification.

They are sometimes referred to as the Smokey Cory which probably arises from the greyish colouration that they possess on the upper half of their body while the lower half is white or yellow. Their front fins can display a yellow colouration but usually the rest of the fins are clear.

Adult specimens can reach a length of over two inches (5 cm) which means that a group of these will require a slightly larger aquarium compared to some of the smaller species but an aquarium that holds 20 gallons (75 liters, 16,6 Imperial gallons) will be fine, for breeding purposes it may be advisable to use an aquarium with a larger footprint as depth does not really play a part in the project and a larger footprint will give them more room for the breeding process.

Like most Corydoras species they can tolerate a fairly wide range of water parameters, pH is not critical as they can live in water with a pH that ranges from 6.0-7.0, the hardness of the water is also not critical as they can live in soft or slightly hard water.

Temperature wise they do prefer the cooler temperature range, setting the heater between 22 °C-26 °C (72 °F - 79 °F) is ideal so they should be housed with tank mates that also prefer cooler water.

Setting up the aquarium for the Corydoras Gossei is relatively simple but they do demand high water quality and their health can deteriorate quickly if the aquarium does not receive regular water changes and thorough vacuuming on a regular basis. They spend a lot of time on the substrate and they do possess delicate barbels so the gravel vacuum will help enormously in preventing diseases and infections being contracted from the bottom of the aquarium.

Plants added to the aquarium will provide cover as will décor such as bog wood, if you are using other décor then make sure that there are no sharp edges that can injure the fish, the substrate should either be sand or a smooth gravel. I also like to use heater guards as this rules out any chance of the fish burning themselves on the bare heater, one less thing to worry about.

The lighting should be subdued as the Corydoras Gossei do not like bright lighting, they may be sluggish in the daytime but do become more active in the evening. I prefer to feed the Corydoras during the evening hours to give them the chance of getting more food when they are at their most active, keep them in small groups of at least 5 specimens to see them at their best as they interact with each other being playful around the aquarium.

Suitable tank mates are other peaceful species of fish such as Tetras or Rasboras, avoid adding other bottom dwellers to the aquarium that can become territorial such as Rainbow Sharks as Corydoras can soon become intimidated.

Feeding the Corydoras Gossei

As mentioned above these fish are most active in the evening hours so this proves to be also an ideal time of the day to offer them food. They are classed as omnivorous and should accept all quality foods that are offered, sinking pellets are ideal as they tend to sift through the substrate when looking for food. Using the sinking pellets also allows then to feed properly without their tank mates getting all of the food before it hits the bottom of the aquarium. They will also require some live or frozen meaty foods to keep them at their best, blood worms, daphnia or brine shrimp are ideal and will be readily accepted by the Corydoras.

For vegetable matter, algae wafers can be used, I prefer to break these into smaller pieces so that they can be spread around the bottom of the aquarium giving all of the fish the chance to have their share.

Unfortunately the Corydoras species were once seen as scavengers and added to the tank to keep the substrate clean, this is not the case and they deserve their own diet so you must make sure that they get their food alongside their tank mates.

Breeding the Corydoras Gossei

When the Corydoras Gossei were first imported there were not many reports of successful breeding attempts but nowadays there seem to be more breeders raising fry which in turn has resulted in more of these delightful fish becoming available to other keepers.

Sexing these fish once they have reached maturity is quite a simple process, you need to look at the fish from above and the females will have a rounder body shape especially around the belly.

To guarantee getting a mixture of the sexes it is best to acquire a group of the fish and grow them on, 6 specimens should ensure at least one breeding pair and hopefully two.

One point that has been noticeable after reading about other breeders experiences is that the males tend to take longer to reach sexual maturity compared to other Corydoras species so you may find that the females may produce eggs that are not fertilised initially but you have to be patient and in time the pairs will produce fry so don not expect quick results with this species.

Some males have reached an age of 3-4 years before being capable of fertilising the eggs.

Setting up the breeding tank is quite a straightforward affair, a small aquarium can be used and make sure that the tank has a large footprint, the depth can be as low as 12 inches (30 cm) without affecting the breeding project.

When setting up the filters in any of my breeding tanks I always prefer to use the air driven sponge filters, there are a couple of reasons for this, the sponges are easy to clean by squeezing them in aged tank water and there is no chance of the fry being sucked into any inlet pipes which would be disastrous. The water flow should be set to low to medium, too much water flow will hamper the chances of the males fertilising the eggs as the sperm can be dispersed away from them. The choice is yours as to whether or not you add a substrate, many breeders use bare bottomed tanks, this does make cleaning the tank a lot easier but others prefer to add pebbles so that some of the eggs can drop through to safety after being fertilised.

Keep the pH of the water below 7.0 and the temperature can be set to 26 °C (79 °F). Softening the water may encourage spawning as will adding cooler water when performing changes as this replicates the rainy season in their natural habitat, a trigger for their natural spawning season.

Patience is the key here as stated above the males can take a few years to mature but they should spawn eventually. The males will start to swim with the female when they are ready to mate and he will caress her with his barbels, just prior to spawning as with all of the Corydoras species, the fish will assume the “T” position when ready to spawn , this simply means that the male will hold the female positioning himself at the front of her mouth parts ready to release the sperm. The female will then form a cage with her pelvic fins and drop an egg into these, the sperm will then pass onto the egg fertilising it immediately.

Once spawning has ceased the parent fish will need to be separated from the eggs or they will attempt to eat them. I find it easier to move the parent fish rather than attempting to move the eggs but the choice is yours.

If the eggs are fertilised they will be an orangey/brown colouration, any eggs that are white after 24 hours are either un-fertilised or they have contracted a fungus, either way these white eggs will never amount to anything.

The successful eggs should hatch in 2-3 days but the fry do not require feeding at this stage, they hatch with their yolk sac still attached and this is consumed before any external foods are required. Once the yolk sacs have been consumed the fry become free swimming and will accept newly hatched brine shrimp, white worms or a commercial fry food for egg laying species. Always remember that the fry have small stomachs and do not require large meals to grow then on, it is far better to provide small meals 3-4 times per day and any uneaten food must be removed from the breeding tank before it gets the chance to decay and foul the water.

Words of warning

There are a couple of points that is worth remembering when keeping any of the Corydoras species, they possess delicate barbels that can become damaged and infected if the substrate is not kept clean.

They also have a barb on their eye sockets which they can raise to dissuade predators, this barb can inflict a sting to other fish and it can feel uncomfortable to humans if they break the skin, try to avoid netting these fish as they can become tangled, I prefer to move Corydoras by trapping them in a container so that they do not get too stressed.