Witt wrote:Every aquarist interested in marine fish propagation undertakes challenges and vexations that can prove dreadfully annoying; this can often last years. Here is a brief synopsis of my epic battle with Abudefduf saxatilis. I thought this might be a good one to post owing to the rearing tanks used and the frustrations encountered.
Each year, as the water temperature slowly rises from the cooling of winter I patiently polish the glass on my diving mask in anxious preparation for the sergeant major spawning season. Usually in late May brooding male sergeants can be seen a good distance away underwater, their bright blue nuptial colors being a dead give away as to the location of their nests. Once the nests are located I place 12" ceramic tiles in a variety of locations near the brooding males. Eventually, one of the males will give and spawn on the tile.
After placing a new tile in place of the old, the tile containing the spawn is transferred back to the lab, inverted and supplied with a steady stream of air. Collecting eggs and hatching larvae is non-problematic and I can usually get over 1,000 larvae from a single spawn. This is an egg shortly before hatching.
I first attempted to raise sergeants 3 years ago. I hatched the larvae in black laundry sinks, fed them rotifers and watched them die. At 5 days there was a massive mortality. I added some wild plankton to the mix and routinely brought them to day 15. There was still a big drop at day 5, but I still got some to day 15. Then, I tried raising some with live microalgae, some with paste, some without rotifers, and several different densities and sizes of plankton, and I was beginning to see progress. Numbers would slowly dwindle until there were 2 or 3 left in the tanks by day 17. Flexion was just barely initiated and I kept thinking I was going to raise at least 1. Then, the next day they would be dead. By the time I thought I was getting somewhere the spawning season would be over and I was out of eggs until the next year. Well, finally this year I have good news. It turns out this is one of the pickiest little fish I have come across.
In the larger systems greenwater definitely reduced mortality. Paste or live, didn't matter.
Food is THE major constraint. I put hours into watching these little guys. Swimming in a soup of potential organisms and they want nothing to do with most of them. While they do consume rotifers, dinoflagellates and a bunch of other organisms they definitely do not survive on it. Copepods...they will hold out for, inspect everything around them, but unless it jerks, jostles or tries to escape they don't seem to be interested. I watched one larva for about 20 minutes the other day inspecting and casting aside roughly 50 potential meals before it came across a copepod. At the sight of the copepod, the larva stopped, curled up into an S pattern, but the copepod moved. The larva relaxed, repositioned and tried again. This went on for over 2 minutes. That larva tracked and stalked that copepod until he finally captured it.
With a good density of copepod nauplii growth is quick and flexion is achieved around day 15. metamorphosis is complete by day 20, usually.
Diet has extreme effects on growth and metamorphosis. In earlier trials no larvae hit flexion until day 17 and the tip was barely flexed up.
Female Starkii Damsel.
121306120 Chrysiptera starcki $19.99
Users browsing this forum: No registered users and 2 guests