|Posted on April 27, 2013 at 10:05 PM|
Yesterday I moved the goby nest in its PVC pipe home to the BRT. I moved them a day early, because I was concerned that I might miss the hatch. So I moved them, and waited, and none appeared to hatch. Came home from work today, and looked for goby larvae. Still no hatch.
Gave up and thought I would clean out the BRT, since it could be used for something else. Then I noticed a tiny goby larva in there! I found the flashlight and discovered a few more. I took the nest pipe and looked at it. There seemed to be fewer eggs there than I remembered. I gave a good Mulcahey underwater shake, waited for a hatch and still nothing. I reattached it to the air bubble stream. 15 minutes later, I came back and noticed one in the water . And what? There's another crowd of larvae over there!!! They were hatching! In broad daylight! It was a good hatch. The larvae seem strong, and are eating the rotifers. After consulting with friend Jim, his gobies hatch in daylight regularly. Huh.
I have a black round 17 gallon tub with baby goby larvae in it. I started this tub 12 days ago with a fresh hatch of Neon Gobies (Elacatinus oceanops). They did alright with just SS rotifers for a few days. I noticed the tub had a lawn of green fuzz on its underwater surface, so I thought it might be time for a sponge filter. I retrieved the pond sponge that has been living in my growout sump forever, put it in a bucket, and hooked up a small powerhead with a T'd off valve to send water back into the bucket, and tubing on the T leading over the edge of the tub. The tub has a central standpipe that drains to the bucket. The valve is so I can control the flow, but it didn't work too well, as I either got too much flow or nothing at all. I started this slow exchange of water for about 4 days, and my goby population dwindled to just a couple .
The next nest of gobies were hatched in the tub, without changing a thing except to turn off the flow. Two days later, there still appeared to be a lot of baby gobies and at least one that is much longer, and I assume is a holdout from the previous nest. I am always happy to see him, Mr. Long, as it will be reassuring to have at least one metamorphosize before the rest of them, in 4 weeks time.
This morning I was re-reading a friend's report, and was reminded that gobies don't like to have water changes. They must be very delicate. Maybe that's why I lost so many when I started the circulation with the pond filter. I'll have to try something different with this batch. I am toping off with fresh water by adding a half of a cup whenever I pass by. The tank is lit 24/7 with a clamp-on reflector fixture and an 18 watt CFL. The majority of the larvae are in a cloud under the lamp, so I think they like the light. Some are on the other side of the tub, in a low flow area. Now at Day 2, the larvae are on the last bits of yolk sac. I expect that the ones who have not learned to eat the tiny rotifers will die off, and it is not unusual to have mortalities on Day 3.
It's hard to say what one's yield is, when the gobies start out as transparent as glass, and the size of a baby's eyelash, and impossible to count. Making it even more difficult is that they are in a black round tub, swimming in a soup of green phytoplankton and rotifers. One can hardly see them without the aid of a strong pair of glasses, and a flashlight when they first hatch. But I have to say, it appears that there were not really significant mortalities more than three weeks later. The cloud of larvae are still a cloud, perhaps as many as 20 little darters, still eating constantly 22 days after hatching, without sleep. They are beginning to show signs of metamorphosis!
About a week ago I slipped a 3/4 inch PVC elbow into the tub, to provide some perching space for the settled gobies. One little guy took up residence almost immediately, and while I can't see him clearly, and he never comes to the surface, I am now sure it is Mr. Long. This goby is completely dark, and has well developed pectoral and caudal fins. I can't see the neon blue stripes, and I can't get a picture, but it has to be him. I am reassured that he alone survived from the first nest, and it makes me feel that I did as well as can be expected for the rest of them.