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Greater Seattle Aquarium Society

Spawning the Black Phantom Tetra

by Susan Jensen

At the time of this writing I have a 10 gal tank full of 3 month old Black Phantom tetra. Their parents spawned on the morning of March 9th and in the afternoon of the 10th I saw the tiny fry, looking like slivers of glass with large black eyes, clinging to the glass surfaces of the 5 gallon breeding tank. This was my second attempt to raise Black Phantom tetra. When I lost an entire spawning the first time I bred these fish, in the fall of ’97, I wasn’t sure if I wanted to try again. What I learned from that experience, though, was valuable and helped me to understand a lot of the more subtle requirements necessary for the successful rearing of tetra fry. To quote Axelrod, The best general advice is that few species turn out to be as particular in the conditions they demand for the successful spawning as most people think and that cleanliness, healthy fish, and proper feeding are often more important than pH, temperature, light, and shade.

I should probably mention that I set up my first tank in September’97. I wanted a community tank of peaceful freshwater fish, so I spent the summer checking books out of the library and studying the families, genus and species that I was interested in. I had no intention of ever breeding fish and so I only skimmed over those sections. At that time, I was very interested in aquascaping and to some degree, focused mostly on plants and selected fish that were sure to get along quietly and happily together. The first fish that I added to my fully planted 55 gallon tank were 6 Megalamphodus megalopterus (Black Phantom tetra). The males can be very entertaining. They have a habit of playing king of the tank where they mock fight by swimming towards each other - large dorsal and anal fins flared - and then tilt sideways at the last minute to glide past. It was easy to distinguish the males: charcoal black body and all fins, from the females: rosy salmon body with orange adipose and ventral fins. Both have black saddle markings behind their gills with a neon silver/blue boarder along either side. It wasn’t long before I witnessed them spawning in the community tank, which they cohabited with pencilfish, Cory cats, and an angelfish. My interest instantly shifted to breeding them and I started re-checking out all those books and studying the sections that I had passed over lightly months before.

The documented approaches on setting up a breeding tank vary to some degree. Black Phantom tetra scatter non-adhesive eggs, which are at risk of being eaten by the breeding adults. Lining the tank with peat, gravel, marbles, spawning grid, or glass rods have all been recommended. Unlike my first attempt to breed these fish, where I covered the tank bottom with gravel, I decided this time to leave the tank bare bottomed. I reasoned that since I would closely observe the entire spawning process, I could remove the pair as soon as this was completed, reducing the risk to the eggs. Because of this, I would have more control over the quality of the water as far as keeping it free of debris and uneaten food. This turned out to be very beneficial.

The 5 gallon tank was set up with one bunch of Java Moss tied to a rock and one bunch of Rotala weighted down with a strip of lead, a 50 Watt Ebo Jäger heater and a sponge filter. I seasoned the water in a 5 gallon bucket for several days with Fluval peat tied in nylon. I kept the water at 82 degrees. The pH remained between 6.5 and 6.7.

Female Black Phantoms are perpetually bulging and ready to spawn. No special conditioning or preparations seem necessary. I placed the female and one of the males into the breeding tank in the evening. Early the next morning, with the sunrise, the pair began their pre-spawning activity. The male was almost jet black in color and held his large dorsal and anal fins flared to their fullest. The female’s coloring was also heightened to a bright rosy salmon with jet black dorsal and caudal fins and with a bright orange anal fin rimed in black. For a time, the female chased and nipped at the male. Eventually they reversed and the male chased the female, who sporadically led the male into both the Java Moss and the Rotala where, side by side, she would release a bunch of eggs and he would fertilize them. This was the first time that I was able to see as the eggs were released and fall to the bottom of the tank around the plants. It seemed like hundreds of eggs were scattered. They looked like tiny glass beads. If I had covered the tank bottom with peat or gravel, this would not have been possible. After several hours the pair became slow and quiet and I moved them back into the community tank.

Tetra fry need darkness to emerge from the egg and also for their first few days of life, so I placed large pieces of cardboard around the 3 exposed sides of the tank. The light remained off. Later that day I checked the eggs and noted that a large portion where not clear but opaque white. I knew that these could quickly become fungused and worried that it could spread to the fertile eggs so I treated the tank with Acriflavin. The next day, with the use of a magnifying glass, I checked the tank for fry. In addition to large brood of fry, I saw patches of eggs covered in a white fungus. Entry from log dated 3/10: The area around the Rotala is heavy with fungused white eggs. There are fry on the sponge and left side of the tank among the white patches. Java Moss area also has scattered fungused eggs. Was advised not to try to remove until fry are free swimming. Decided to siphon up the largest patch of fungus anyway. The fry are so micro in size. I have no idea how many. Am worried they will be infected with the fungus.

Excerpt from a later log entry: Read about different types of fungus in Handbook of Fish Diseases by Dieter Untergasser and discovered that the infertile eggs were infected with Saprolegnia fungus. Acriflavin is not effective for this strain. Recommended treatment is Methylene Blue!

I later read in Exotic Tropical Fishes by Axelrod, Emmens, Burgess and Pronek: Infertile eggs quickly become opaque and fungused, looking like a powder puff with white filaments of fungus sprouting in all directions. Fertile eggs lying next to a mass of fungus-covered infertiles may be attacked, but they usually remain unaffected.

I began doing water changes that first day. My intention was to remove as much of the fungus covered eggs as I could without disturbing the fry. I used 1/8" tubing cut at an angle at one end. With good lighting and the beveled end held almost flat to the bottom of the tank and always ready to stop the flow at the opposite end with my free hand, I siphoned away most of the fungus without risking the fry. It took a steady hand and nerves of steel, but I soon became more comfortable with this process as it would be a daily task for more than 2 months.

I kept the tank dark for the next few days. On lighting: from one of the text books, [Tetra fry] need subdued light with strong occasional shafts of penetrating brilliance. Their eggs are best hatched in utter darkness, maintained for 5 full days. During this time fry are being nourished from their yolk-sacs. The majority of my fry retained their yolk-sacs for around 3 days - duration varies in text books; it probably depends on specific species. When their yolk-sacs were fully absorbed they would begin taking other foods and be able to swim freely. In preparation for this stage, I added Liquifry No.1 two to four times a day to begin cultivating the various organisms that they would feed on.

Over the next few weeks I gradually increased the amount of light in their tank. I filtered the light from the hood by covering it with black press board in which I cut holes to allow only small amounts of light through. I still used cardboard around the sides and part of the front of the tank to limit the amount of daylight.

Log entry 3-15 (5 days old): I do a micro water change every day in the fry tank. They look healthy. The tank conditions look good. Lots of planaria (small worms) on the tank glass. Count about 30 fry. Could be more.

I spent a lot of time watching the fry through a magnifying glass. Many stayed under the edge of the sponge filter, some clung to the heater, sides and bottom of the tank. I was able to observe them feeding on the small cultured organisms that grew on all surfaces. Over the course of days, I realized that their diet needed to be increased to include other live foods, as their supply of planaria was decreasing with their increasing appetite and size.

Unfortunately, I didn’t plan far enough ahead as far as their diet was concerned. As Jorg Vierke says in Vierke’s Aquarium Book, Many a hopeful breeder has seen his young brood starve. There are still species for which provision of the right food for raising is problematic. I think he may have been referring to tetra fry, in general. They are so tiny that the question soon becomes what to feed them and when to change their diet.

The fry had not yet reached 2 weeks old and I was afraid that there was not enough food being cultivated in the tank to sustain them. I was in a slight state of panic when I began checking resources for a microworm culture, only to discover that it would take longer to obtain than I had anticipated. A week elapsed before I was able to get the culture. In the meantime I started a batch brine shrimp eggs. The fry were so tiny; I was concerned that the nauplii would be too large for the fry to eat. At this stage the fry clung to the glass or hung motionless just off the sides and bottom of the tank. On 3-24 I fed them their first meal of nauplii and was relieved as I watched them snatch at the minute crustaceans with quick jerky motions. Within minutes their stomachs were bright pink and swollen with the food. I knew now that the fry would thrive!

Soon I became efficient at timing the hatching of brine shrimp eggs, always alternating between two gallon jars. Their diet quickly became varied between nauplii, microworms, crushed frozen blood worms (with mortar and pestle), and powdered baby fish food and eventually ground flake food.

On 3/21 I have noted one dead fry and on 3/23, removed 3 dead fry. These would end up being the only fry that died from this spawn. Using an 8X magnifier, I made a sketch of an 11 day old fry. Size around 5/32".

Entry from log 3-30 (20days old): Have been feeding the fry nauplii for 6 days. Some of the fry are much larger than others. They will not eat powdered fry food. I have no way to get an accurate count of how many there are. They stay in the cover of the Java Moss and under the sponge filter. Continue to use Liquifry No. 1 for the smaller fry.

Entry from log 4-4 (25 days old): Fry are eating microworms and baby brine shrimp. Also feed powdered flake food in the mornings, but have never seen them eat it. I have counted 30+ fry at one time. There may be more. Fry look very healthy. They have developed caudal fins and their eyes have changed from big black spheres to flat silver disks with small black dots in the center (like the adults). Their stomachs are round and full after feedings. They eat well and are getting big. They are staying in the open with more frequency. Even when I siphon off the bottom debris, they don’t dart away and hide anymore. Am pleased with their progress. Some are smaller and less developed.

Entry from log 4-6 (27 days old): Fry are feeding between 1" - 3" off the bottom, taking food out of the water. Only after the nauplii are exhausted from the water and settle to the bottom do they start feeding from the bottom again. They are still rejecting flake food. Have observed a fry take in a flake and spit it back out. They are starting to exhibit the Black Phantom tetra behavior of darting at one another. Many are out in the open in groups most of the time. Some still hang out under the sponge filter and Java Moss. The fry have developed distinctive dorsal and anal fins. Their bodies appear more iridescent and have a grayish cast across their backs. Size around 5/16". Counted around 31 fry - there are probably more.

Entry from log 4-7 6pm (4 weeks old): Just counted 50 fry. At this time of day most of them are out in the open, resting just off the bottom. A few of the fry are larger with more developed black tipped dorsal and anal fins. The majority are paler in color. Their shape is less pot-bellied and sleeker. Around 3/8" long. Noted that the largest are taking food at the mid tank level. Their bodies have a light gray cast in certain lighting.

Entry from log 4-19 (5 ½ weeks old): The fry have changed a lot since last entry. On the 14th I noticed that the fry school. On the 18th fry ate powdered flake food! Today I noticed faint beginnings of saddle markings. Most of the larger fry have well developed (large) black dorsal fins and black edged anal and caudal fins and have a vertical black stripe across the eye. Their ventral fins are very prominent. I believe there are over 60 in number. Some are now around ½" in length. The color of their bodies is still pinkish gray. Their stomachs are light pink

On growth: from Exotic Tropical Fishes, by Axelrod, Emmens, Burgess and Pronek: Very young fry tolerate surprising degrees of crowding. The fry of nearly all tropicals can be kept in the small 3-5 gallon breeding tank for the first 4-6 weeks.

Entry from log 4-22 (6 weeks old): Transferred the fry to a 10 gallon tank on the 20th. Concerned with getting same water conditions in the new tank and moving the heater and sponge filter without shock to the fry. Main concern was actually moving the fish. Read that it was not a good idea to net the fry. Ended up siphoning using ½" tubing. All fry survived. Got white worms in the mail today.

Entry from log 4-23: Placed white worms in potting soil/peat mixture. Extracted a clump by placing soil on a piece of screen over a container of water and placing a light over the top. Worked well. Will feed fry chopped worms in the morning.

Entry from 4-25 (6 ½ weeks old): Larger fry display the most vibrant colors and developed finnage, particularly dorsal and anal fins. Most fry have developed their adipose fin at this point. Is orange on all fry. This fin is orange on adult females and gray on adult males. Since all fry are still rosy salmon in color it is not possible to determine their sex by this. The saddle markings are growing more distinctive on the larger fry. Some of the less mature ones still have only the beginnings of this marking. I fed ground flake food with spirulina this morning. They eat it but not enthusiastically.

Entry from 4-27 (7 weeks old): Ground flake food for first feeding this morning. Fry are starting to dart to the surface to snatch at the tiny flakes. Others still graze on the bottom and all points in between. Their sizes and intensity of color on their finnage varies as greatly as their behavioral development. Some still have the more rounded appearance to their head (like drawing from 4-6), yet all of their fins are developed. All fry have orange colored ventral and adipose fins. In general, fry are becoming broader in width. Their bodies are shiny pink/salmon in color. No sure way to determine males from females. What is easily distinguishable in the adults, cannot be determined yet in the fry, even by size and shape of the dorsal fin. Roughly count around 70 fry. Water changes are getting easier - at least on my nerves. Am not afraid of siphoning up fry as I vacuum the bottom. They are so large. They swim around my hand and are less startled as I move through the tank. The pressure from the siphon doesn’t phase them anymore. Water tested fine: pH 6.7, KH 1 degree, ammonia 0 ppm, NO3 0 ppm. Keep the temp @ 82 degrees w/barely 1 degree variation. No uneaten food or waste remains in the tank for more than 12 - 14 hours. Am still seasoning the water in 5 gallon bucket with nylon covered peat ball. Return water slowly into the tank with 1/8" tubing.

Entry from 5-19 (10 weeks old): Switched to ½" tubing (bevel cut at one end) for siphoning at water changes a couple weeks ago. Much easier and faster. Still return the water slowly, but use 2 lengths of 1/8" tubing, now. Started running the Aqua Clear mini filter on the 16th. Still run the sponge filter also. Change water every other or every third day, now. The water is clean and clear. Still replace with seasoned peat soaked water. Add hot water to bucket to reach 82 degrees and condition. Combined both bunches of Java Moss and keep it on the bottom with a lead weight only. No rock or substrate in the tank. Fish are healthy, active, and getting big. Rough measurement is around ¾". Some still smaller by as much as 1/8". Body color is still rosy salmon. Color intensity of fins vary from intense black to pale gray. Ventral and adipose fins are orange. Saddle markings very distinctive with pale neon boarder. The fish show no fear when I clean the tank and even school around my hand. At feeding time they crowd to the front of the tank.

Within the next week the juveniles will be moved into a 20 gallon tank. In about one month the fry will be old enough to be added to a community tank with other compatible species. I will probably keep only 10 of the fish for myself and will be sad when the day comes to give up their brothers and sisters.