Moenkhausia pittieri (Diamond Tetra) Spawning Report
Submitted by Patchin Crandall Curtis
Background: The diamond tetra is found in shallow, vegetated parts of Lake Valencia, as well as in several slow-moving tributaries. Lake Valencia and its watershed is situated between two picturesque mountain ranges in Venezuela. Lake temperatures are tropical varying from 75o – 82oF. The lake surface is at an altitude of 410 m (1,350 ft), the maximum depth is 39 m, and the mean depth 18 m. The lake has a number of small islands, some inhabited. Lake Valencia suffers from algal blooms caused by continual influx of untreated wastewater from the surrounding urban, agricultural, and industrial land uses. This contributes to ongoing eutrophication, contamination, and salinization of the lake negatively impacting this gorgeous community fish.
Colony: Purchased pond-raised males from Matt Chambers on 1/6/2018 and wild-caught females from the Wet Spot on 4/17/2019. The current colony consists of 5 males and 3 females. They are kept at 76oF. I have experienced losses when water temperatures were consistently higher than 78oF and thus believe that they enjoy better health when maintained at the lower end of their reported temperature range.
The wild-caught females were juveniles when the fish arrived in April. They were grown out on a diet of Repashy Igapo Explorer and Soilent Green, and New Life Spectrum, Cobalt, and North Fin brand community pellets. At least twice a week they were fed a variety of frozen foods. When a single fry somehow survived in a community tank with other tetras, I decided it was time to undertake some controlled spawning experiments.
Tank Set-Up & Spawning: On 9/15/2019 a 20L tank was prepared with a coarse gravel bottom to catch eggs (CaribSea Joe’s Creek), 2 pieces of Malaysian driftwood with Christmas moss attached with black silicone hairbands, and spawning mops dangling down in the corners suspended from Styrofoam floats to simulate the overhang from vegetation at water’s edge. A 50% water change was performed with 50/50 tap water/RO mix. Flourish fertilizer was added to help establish the java moss, and Tetra Black Water Extract was added to stain the water and provide tannins. Water temperature was set at 77oF. In the evening, the fish were netted out of the community tank and placed in the 20L. The next morning, a catalpa leaf and an alder cone were added to the tank along with a disk of Repashy Igapo Explorer. The lights were turned off and the fish took refuge in the darkened corners of the tank underneath the spawning mops where they remained hidden and inactive. After waiting 15 minutes, I turned off the air supply thereby cutting off the current. The fish then moved into the center of the tank and started to swim around to investigate their surroundings but after 2 hours became inactive again, so I turned the air back on adjusting the flow to be moderately slow. They perked back up again, with males lazily circling each other but no overt spawning behavior. After a few days of heavy feeding, the males appeared to display to each other but I never saw a direct spawn with a female.
On 10/1/2019 the Diamond Tetras were removed to repurpose the tank for quarantining Croaking Gouramis for the Spring All-Day Auction, and then some newly purchased Sharp-Nosed Chocolate Gouramis. The tank was thoroughly siphoned and cleaned a couple of times between fish shipments. At this point, my working assumption was that any eggs deposited by the Diamond Tetras had probably been either eaten or siphoned out, or the fry eaten by the Gouramis.
Raising Fry: Then, on 10/18/2019 after feeding the Chocolate Gouramis heavily on newly hatched BBS, I noticed a bunch of relatively large, plain, silver fry with full guts that looked near to bursting. The first day I could just see 6 or so, the next day 8, and then 12 the next. They hide very effectively in the floating plants and among the driftwood and java moss. They are already quite large ranging from 5 mm to 1 cm in length. Their maximum possible age is 5 weeks old, so the fry must be very fast-growing compared to Blue Emperor Tetras which would take at least 12 weeks to reach a similar size.
On 11/1/2019 the tank was thoroughly cleaned and the fry placed in a clear container to be photographed. The fry are somewhere in the range of 4-6 weeks. They may be from a single spawn or multiple spawns sometime during the last 2 weeks of September.
The adults are gorgeous. Makes me want to get some.
great photos by the way...
Very nice write-up Patchin! Thanks so much for sharing the setup details. I also watched Marks Video on youtube and setup a 10G tank and added a conditioned pair. I took them after 2 days after witnessing spawning behavior. I am hoping that they would have spawned and will see some fry in the near future. They take ages to show up! They are critically endangered in Lake Valencia!
Hello Patchin,
This is to confirm that you have been awarded 20 points for your Diamond tetra fry and 5 additional points for your detailed spawning report/article for a total of 25 points
Thanks,
Raychel
New Spawning Approach
Although the group spawning in September, 2019 produced a dozen or more fry, I wasn’t convinced that this was the ideal spawning setup for Diamond Tetras so decided to give it another go. In an excellent YouTube video by Mark’s Aquatics on “Breeding Diamond Tetras Part 1” (https://www.youtube.com/watch?v=kHlLQZrADsM), Mark notes that Diamond Tetras prefer to spawn in pairs, and a male will show a preference for a certain female. When selecting pairs to spawn, the fish keeper should note any natural pairings that may be forming. Otherwise, you may have to try a couple different pairs.
Tips from Mark’s Aquatics
1) Provide a bit more room – 10g tank is good
2) Select compatible pairs where the male and female are similarly sized
3) Separate male and female prior to spawning and condition with high protein foods
4) Mix used tank water having neutral pH with 50% rainwater
5) Add botanicals like leaves
6) Pace spawning mop on bottom of tank in back corner by heater
7) Raise temperature to 26oC (79oF)
This was consistent with my own observations, so armed with this new strategy on 1/6/2020 I set up a 20H with a soft sandy substrate (CaribSea Sunset Gold), some Malaysian driftwood wrapped in java moss, and a large ball of java moss in the back corner next to the mattenfilter and under the heater. The tank was heated to 76oF, had just been thoroughly cleaned and given a 90% water change before introducing the pair. Soft, neutral tap water was used. There were no botanicals in the tank other than the driftwood and java moss so the water was not particularly tannic.
I introduced one pond-raised male (about 30 months old) and one wild-caught female (about 14-18 months old) into the spawning tank mid-day when the lights were and the tank was bright not expecting to see any action until the following early morning hours. The male immediately began twitching, dancing, and chasing the female all around the tank. It seemed as if he had been awaiting the right moment and circumstances for ages. After a couple of hours, and no actual spawning, they settled down for a couple of hours until the white lights went off and the blue, night lights were on. Then it was game on again. I’d never seen tetras spawning in the evening before. I couldn’t see an actual spawn because the pair would dive down behind the java moss. Early the next morning, they slept in late and I got bored and distracted and went upstairs for coffee and whatnot and got distracted. When I finally checked in again in the late afternoon there were eggs everywhere. The fish were calm and strangely showed no interest in eating the eggs, perhaps because there was a disk of Repashy Soilent Green food. I fluffed up the java moss in the hopes that a good number of eggs would fall to the bottom and be shielded from view. I also unplugged the light fixture so that eggs on the surface wouldn’t be exposed to any more light. The eggs on top of the java moss exposed to light quickly developed fungus. I believe the eggs that had fallen below and were protected from light did not fungus, but time will tell.
I kept the pair in the tank for a total of 6 days hoping to actually witness a spawn. By the third day, they showed no further interest in spawning, so I performed a large water change with 50% RO water, added a couple of boiled alder cones, and added some Tetra Blackwater Extract. The male immediately went into high spawning gear again. On 1/11/2020 there were more eggs on top of the java moss. Once again I gave the moss a good shake hoping to get the majority of eggs out of the light, and on 1/12/2020 I moved the pair back to the colony in a 50g Breeder. I also unplugged the light fixture for 48 hours to provide the eggs with as much dark as possible until they hatch.
Next, I will monitor the 20H spawning tank for fry and add live infusoria.
UPDATE 1/15/2020: See one free-swimming fry and ~7 larval fish hanging on the back glass in the shadow cast by the heater. They are moving around in response to the small flashlight and my movements. Added a bunch of live infusoria from my "high-octane special blend" of rotifers, euglena, paramecium, blepharisma, and goodness knows what else that could have come in on oak leaves and java moss added to the bucket to stew. As soon as I added the infusoria, the free-swimming larval fish started moving around the tank hunting food.
Great looking, well fed fry.