Spawning the Paretroplus damii - Page 2: Waiting for the Fry to Swim
Spawning the Paretroplus damii - Page 2: Waiting for the Fry to Swim
Written by Monday, 07 February 2005 00:00
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| Spawning the Paretroplus damii |
| Page 2: Waiting for the Fry to Swim |
| Page 3: Raising the Fry |
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by George J. Reclos and John Reclos
Waiting for something to happen is not my strong point. However, we (Johnny and I) knew that there was no way (or reason) to force things. All we had to do is to sit back and wait for the process to finish. Or not ? I have spent tens of thousands of hours on the internet and I have never seen any good quality photos of the eggs or the development of the fry after they hatch. So, the camera was there, the extension tubes ready and polished, what else did we need ? Apart from the useful information this may give other hobbyists it was a very nice way to keep us busy. All photos were taken at 24 hour intervals. Time "0" is when we saw most of the eggs hatched and transferred them to their floating net - nest. Since it took about 8 hours for most of the eggs to hatch, the time points are defined as day+8 hours. The eggs are tiny and you need to break the 1:1 magnification ratio to get some decent photos of them - with enough detail. We chose 5 photos from each day - all photos were taken during 5 minutes (we didn't want to mess with the fry more than that).
One day later (24-32 hours after hatching), the yolk sack has diminished in size, the developing eyes are far more visible while there is a black line on the top of their bodies.
After the completion of the second day post hatching (48-56 hours after the eggs hatched) the little creatures show very few external changes as compared to a day before. The most notable ones are the appearance of a silver circle around their developing eyes and a pink formation, barely visible in some of them, which is probably an internal organ (I figured it is a bit to the back to be their gills). Moreover, the black line has intensified.
After the completion of the third day (72-80 hours after the eggs hatched) there is not much to report. I am sure that those of you with a relevant scientific background may notice more differences in the development of the fry - this is part of the reason those photos are online. It should be noted that the fry of Paratilapia sp. Andapa are already free swimming at this age. It would be interesting to notice the difference in the development of the fry between those two species (Pe damii and P. sp. "Andapa"). By this time (almost 7 days after the pair spawned) the P. sp. "Andapa" fry are already free swimming. However, this is partly due to the mass of the yolk sack the fry carry at the time of hatching, which is - obviously - proportional to the egg size. As you can see here, the P. sp. "Andapa" fry carry a much smaller yolk sack at the time they hatch (smaller than the one the Pe damii still have, 3 days after hatching). Furthermore, the "Andapa" fry sack is rapidly reduced in three days, while it takes ages for the sack of Pe damii to do the same.
After the completion of the fourth day (96-104 hours after hatching; yes, it takes a long time for them to become free swimming) there are some obvious differences. First, the yolk sack is obviously reduced in size during the last day, which is very evident in the bottom photos of the last two days. As you can see, the sack is not pointed at the end but round and shorter. Second, the gill covers are evident and are still disproportional (too large) compared to the head and body of the fry. Third, you can see the little mouths which are already shaped. You can also note the increase in the intensity of the black markings on their bodies as well as the eyes which now look as fully formed. The fry will still try to swim which results in circular moves around the net frame. When they get tired, the water current brings them all together and all you can see is a dark brown "vibrating" mass. This was also the first time that we saw fry resting in the normal (vertical) position instead of lying on their side.
After the completion of the fifth day (120-128 hours after hatching) it was obvious that this diary had come to an end. Some of the fry were already free swimming while most of them were able to take the vertical position and keep it for much longer. As time passed by, more and more fry were able to make long jumps which soon became swimming attempts. It was evident they would soon need food so they had to be removed in the special tanks prepared for this reason, following our discussions with Sonia and Dave in Vichy. The net floating nest was destroyed by Johnny and me to avoid any trapping of the fry between the frame and the net and the net with the fry was removed in a container with water in their new home. As far as we know, they didn't come in contact with air. A limited number of fry were left in the bare bottom tank to test another hypothesis. I really hope you enjoyed this diary as much as we enjoyed creating it.
All photos of this set were taken with a d-SLR Nikon (D70) with a Tamron 90mm f/2.8 macro lens (1:1) on which 75 mm of extension tubes were added, yielding a magnification of almost 2:1. All settings on the camera and the flash unit were set on manual (including focusing). For those interested, they were shot with an f/22 - f32 (for maximum depth of field) and full power flash. Further magnification was not possible in this particular setup since the lens would touch the water. Next time I may use a shallower tray and even greater magnification with a focusing trail.
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