We've successfully finished our 30 days with a small batch of corydoras aeneus (11 fry). Guess this will be the last BAP submission for 2020 for us. Learned a lot with this project. Took a year of growing the Corys bought from our LFS, and a solid 8 months mounting up failures to figure out how to raise them. We're raising up a larger batch of fry behind these (ca. 20-25).
(1) Eight months ago . . . setting up a dedicated Cory breeding tank
(2) Nov. 20, Cory eggs pulled
(3) Nov. 22, Cory fry free swimming (11 fry counted)
(4) Nov. 30, Fry growth and updates
(5) Dec. 7, Two-week Journal - Chemistry Discussion
(6) Dec. 11, Update and New Batch of Fry following up behind Our BAP batch
(7) Dec. 24, Cory fry BAP graduation - adding fry (11) to adult breeding tank
PVAS BAP SPAWNING REPORT
24 December 2020
Method of Reproduction: Egg Layer
Number and Gender Distribution of Parents: Eight Adults, Possibly only 1-2 Males
Origin of Parents: Tank Raised (Purchased from LFS)
Approximate number of fry: ca. 11
Date of Birth: Free-Swimming (11/22/2020)
Number of Fry at 30 Days: 11
Spawning Tank Size: 20 gal. long
Spawning Tank Water Source: town / city water
Spawning Tank Water Changes: 30-50% 1x per week / bi-weekly
Spawning Tank Filtration System: Two sponge filters
Spawning Tank Temperature: 78-degrees Farenheit
Spawning Tank pH: 6.0 (water changes cause fluctuations up, but it always drops)
Spawning Tank KH: Unreadably low (tap water is ca. 4 dKH, ca. 71.6)
Spawning Tank Ammonia: 0 ppm
Spawning Tank Nitrite: 0 ppm
Spawning Tank Nitrate: ca. 30 ppm
Note: This tank has experienced a recent pH crash due to humic acid buildup from leaf litter decomposition and alder comes. We removed most the leaf litter and cones, and have been monitiring it’s chemistry.
Specimen Container: 1/2 gal. Lee’s large specimen container
Specimen Container Water Source: Bottled (RO) water
Specimen Container Water Change: 16-32 oz. / day until sponge filter added after 2x weeks
Specimen Container Filtration: None, just air line for 2x weeks; then small sponge filter added
Specimen Container Temperature: ca. 80-degrees Fahrenheit
Specimen Container pH — ca 6.0 (due to use of RO bottled water) and catappa leaf litter
Specimen Container GH — Hard to determine . . . very low
Specimen Container Ammonia: actually Ammonium - can be very high, 0.5-0.8ppm)
Specimen Container Nitrite: 0 ppm (after sponge filter added)
Specimen Container Nitrate: 40-80 ppm (very high)
Note: Specimen Container readings taken after period without water change
DECOR & ENVIRONMENT
Spawning Tank Live Plants: Pothos (roots only), Cryptocoryne Parva
Spawning Tank Caves or Similar Hiding Places: Rocks from stream (boiled before adding), wood
Spawning Tank Substrate: Fine white stone (looks like coarse sand)
Spawning Tank Lighting Type and Timing: LED, 5,000 K, filtered through diffuser, ca. 14 hrs / day
Specimen Container Live Plants: None; only catappa leaf litter and alder cones
Specimen Container Caves or Similar Hiding Places: None until sponge filter added
Specimen Container Substrate: None; again, only catappa leaf litter and alder cones
Specimen Container Lighting Type and Timing: LED, 5,000 K, filtered through diffuser, ca. 14 hrs / day
Food Fed to Parents and How Often: 2x / day. Frozen Blood worms, Bug Bites flake food, wide variety of flake mix - Omega One, Kelp Flakes, But Bites Tropical Blend; live baby brine shrimp
Food Fed to Fry and How Often: 2x / day. Live baby brine shrimp, arctic copepod powder, sera micron, New Life Spectrum fry starter powder, finely crushed flake food
COMMENTS & ADDITIONAL INFORMATION
We couldn’t keep track of the number of times our Corys laid eggs, we collected, and they either failed to hatch, or failed to survive. The factors were manifold. We suspect there may only be one or two fertile males in the original breeding group. Many eggs were just not fertile. We also struggled with fighting off fungus spread in the hatching container. In the end, we were successful using two pieces of catappa leaf and a few alder cones that grow wild out on the edge of some swamps where we live. These release tannins, which help to fight off fungus spread. Also, the decomposition creates lots of context of microlife to flourish for baby corys to get their earliest source of food.
Before we were really successful we tried a lot of things to trigger spawning: heavy water changes; using rainwater / ground water for water changes; cold water changes; feeding a wide variety of foods; over-feeding / cleaning after; altering lighting plans; leaving lights on at night; addition of live plants (crypts); addition of a small Hydor powerhead for flow . . . and then we had the afrementioned challenges of trying to hatch eggs and keep fry alive.
Documented successes from folks in our fish club helped us, as we read some of their BAP submissions. It seems that if you’ve got a decent ratio of mature males and females, feed well, and keep their water quality up, they’ll do their thing eventually. We’ve had our adults for about a year before setting up their breeding tank, so, as with other catfish, they seem to take their time maturing to a breeding age.
Once we had fry, we changed out the water regularly with R. O. Bottled water. But once we were about 2-3 weeks in, our corys spawned again. So we started another batch but just used tank water instead of R. O. water. That batch is going very strong - about 20-25 fry — plus, we found 5x fry from that batch in the parent tank that must have been attached to leaves somewhere.
Some chemistry things we learned / are learning: (1) Raising fry in the little specimen containers is a stress on fish fry, and on fish breeders. Constant vigilance is needed to keep parameters from danger zones. Without filtration, ammonia and nitrite build up quickly. But with a sponge filter, nitrate builds up quickly as well. (2) Using catappa leaf litter and alder cones releases humic acid, and really makes pH dive. This keeps ammonia (NH3) buidup below the 7.0 pH threshold to ammonium (NH4+) which is _slightly_ less problematic for fish . . . but really not good in any way (3) R. O. Water, and our soft tap water, lacks buffer which prevents against pH crashes. We found that the pH crashed in the adult tank when we added some tetras, and kept finding them dead. We originally added a lot of catappa leaf litter and oak leaf litter along with alder cones to the parent tank. It was just too much, and as humic acid built up over time, the pH crashed — from 7.8 tap water to 6.0 (or lower . . . our kit really doesn’t measure pH lower than that).
Science aside, the jury is in: Cory fry are the cutest fish fry in the world! We all love watching them wiggle around. I think this species is one we’ll continue breeding and raising up for a while. Our fish stores are always happy to have some to sell. But we will probably not hold them in the grow out context much beyond 3 weeks so that they can be added into the larger colony and grow up in a better environment.