Corydoras knaacki (Morse Code Cory) Spawning Report
Submitted by Patchin Crandall Curtis
Background: Morse Code Corys are found in southeastern Peru in the Madre de Dios basin west of Puerto Maldonado. They are a lively spotted Cory with horizontal rows of spots on their bodies contrasting with the vertical rows of spots on their caudal fins. This is an easy-to-keep, easy-to-spawn, robust and prolific Cory.
Breeding Colony: Purchased 13 F1 juveniles in late 2019 separately from David Snell and Don Kinyon who had each collected their breeding colonies in Peru the year prior. The juveniles grew very quickly to adult size and exhibited spawning behavior by 9 months of age.
Spawning Tank Set-up: In August, 2019 the colony was moved into a 20H tank with a sand bottom (CaribSea Sunset Gold) and a couple of potted plants. Filtration was provided by a poret foam Mattenfilter. Water temperatures were maintained at about 75oF and 50% weekly cool (72-74oF) water changes were performed. Water was soft and neutral. The fish immediately began to spawn leaving anywhere from 20-40 eggs on the glass in a single night. For the first couple of weeks there was very little plant or other cover and thus a low probability that any larval fish would survive.
On 9/3/2019 I collected about 30 eggs from the glass and removed them to the safety of a hatching tank. The eggs were clear to pale tan in color and measured about 1.5-1.8 mm in diameter.
Hatching Tank Set-up: A 10g tank with a bare bottom, sponge filter, and heater was set up to receive eggs from the Corydoras knaacki and Nematobrycon lacortei spawning tanks. The tank temperature was 71oF for the first couple of days so an additional heater was added to bring the temperature up to 75oF.
Hatching Eggs: None of the eggs moved to the hatching tank hatched. The hatching tank was abandoned in favor of keeping the eggs in situ with the parents and accepting losses from parents eating eggs and perhaps larvae.
On 9/5/2016, 3 fry were spotted scooting around the 20g spawning tank. These were estimated to be a month old and so had apparently hatched and survived despite the lack of cover. A small piece of driftwood with Christmas moss growing on it was added to provide cover for additional larval fish.
By 9/13/2019 at least 12 tiny, spotted fry were counted feeding all along the mattenfilter, driftwood, and java moss. They exhibit no fear of the adults even at this small size.
Raising Fry: The tank was given periodic small doses of rotifer, euglena, paramecium, and Blepharisma cultures, but the primary food source consisted of Repashy Igapo Explorer, Soilent Green, and Redrum on ceramic disks serving as recognizable feeding stations. The tiny fry didn’t seem dependent on the Repashy, which seemed merely to supplement a main diet of micro-organisms residing on the mattenfilter and botanicals.