Cory catfish lay up to two hundred eggs, attaching them to various surfaces in the tank in many small clusters. The female fish carries her eggs between her pectoral fins, where the male fertilizes them. Cory catfish eat their eggs, necessitating the separation of the eggs from the adults.
For the cory catfish to have a successful spawn, certain environmental conditions, such as the correct water level, temperature, and food, must be in place. Cories are known for their peculiar method of fertilizing and transporting their eggs during spawning.
Do Cory Catfish Lay Eggs Like Other Fish?
Cory catfish do lay eggs and are known for having a unique method of fertilizing and transporting their eggs. Spawning can extend over several days. Your ideal male-to-female ratio for cories is two to three males for every female. Female cories are not particular and will mate with any available male.
The initiation of egg-laying happens with the male vigorously pursuing the female. When the female mate with a male, they form a T-shape with the female’s head touching the vent of the male’s body. The female cory forms a cup-like container with her pectoral fins before depositing a couple of eggs into the cup.
Scientists are still researching how fertilization occurs. The current thought is that the female ingests the sperm before blowing it over the eggs through her gills. Or the sperm moves through her gut to mix with the eggs before the release of the eggs occurs.
She then transports the eggs, still held between her pectoral fins, to a hatching site she had carefully prepared earlier. Because the eggs are sticky, the female cory can deposit her eggs on any available surface, with the smooth glass surface of the tank being a common choice.
How Many Eggs Do Cory Catfish Lay?
Cories initially lay very few eggs to kick off the egg-laying process, laying between one and ten eggs in the first batch. Repeating this process several times adds up to approximately two hundred eggs per spawn (for the larger species). The eggs are white and vary between one and two millimeters in diameter.
How Can You Tell If A Cory Catfish Is Pregnant (Gravid)?
Many people refer to egg-bearing fish as being pregnant. Pregnancy only applies to fish or mammals that bear their young alive. The correct word to use for pregnancy in egg-laying fish is gravid.
Your gravid cory catfish will show subtle behavior and physical signs that she is starting to bear eggs.
- The female cory will appear rounder or more plump than usual or show signs of difficulty swimming when she is close to releasing her eggs.
- She will become more solitary in behavior, hiding away and frequenting the empty, quiet areas of the fish tank more often.
- The male fish will start giving the gravid cory more attention, constantly following her around.
- Finally, you may be fortunate enough to see the classic t-shape that forms between the female and male fish during fertilization of the eggs.
Artificially Stimulating Cory Catfish To Lay Eggs
Certain conditions must be met for the cory to lay its eggs successfully. Cory catfish can be fooled to start spawning in an aquarium setup by mimicking what happens in nature.
- Start feeding food sources, such as bloodworms, brine shrimp, good quality flake food, and sinking pellets to stimulate egg-laying in the cories.
- Aquatic plants, filter tubes, aquarium glass, heaters, driftwood, and moss are surfaces in the breeding tank that the cories can use to attach their eggs.
- Smooth gravel or substrate should cover the bottom of the tank, but a clean bottom tank is also suitable for some species.
- Reduce the water level in the tank to simulate the water levels dropping in nature before the rainy season commences.
- To imitate the rainy season in nature, start adding cool, aerated water to the aquarium. Repeat this action daily. Keep the water slightly acidic to neutral pH (6.5 to 7.0) and a temperature a few degrees (about 3 degrees) cooler than usual.
How Do You Know If Cory Catfish Eggs Are Fertile?
Freshly laid cory catfish eggs are white and between one and two millimeters in diameter. After a couple of days, the eggs change to a yellowish-beige color. A central black dot also becomes visible. Unfertilized eggs appear white or translucent.
After-Care For Cory Catfish Eggs
Immediately after the eggs have been laid, you need to remove them to a fry container or a separate rearing tank, as cory catfish are known to eat their eggs. Use a razor blade to remove the eggs from smooth surfaces (such as glass), or use your fingers to roll the eggs off gently. Alternatively, remove the adult fish from the spawning tank and place them in another tank.
The eggs can quickly become infected with fungus once egg laying has taken place. Unfortunately, many eggs are lost this way. To kill the fungus in the water, add Methylene blue and change the water daily. Be aware that the dye will stain everything in the tank with a blue tinge. Cherry shrimp readily consumes dead eggs, helping to reduce potential fungal issues.
How Long Do Cory Catfish Eggs Take To Hatch?
Eggs hatch within three to five days, depending on the cory species. The tiny cories are born with the egg sac still attached and will feed off the egg sac for two to three days. After the egg sac has disappeared, the fry will feed on the protozoan organisms in the water. At this stage, consider introducing powdered food to the fry.
How Often Do Cory Catfish Spawn?
In nature, cory catfish will only lay eggs during the rainy season. In favorable artificial conditions, the catfish can be stimulated to spawn every seven days, which makes them an ideal species for commercial aquarium fish breeders.
When Do Cory Catfish Reach Maturity
The juveniles will reach adult size in approximately one year, although this may vary in species and how at about twelve to eighteen months. Entire clutches of eggs of some of the cory are sometimes infertile, and it may take some species an extra twelve months to produce their first fertile eggs.
How Old Do Cory Catfish Get In Captivity?
Corydoras species can easily survive five to fifteen years in a well-maintained aquarium. Their most significant threat to them is improper handling techniques and a poorly maintained tank environment.
Cory catfish do propagate by laying eggs like other fish. They can be prolific egg layers, spawning every seven days under ideal conditions. Cories are popular fish among fish keepers for their peculiar spawning method and ease of looking after.