Thursday, October 31, 2013


Today was a real bummer.
I woke up to the larvae just under the surface with rapid respiration and hanging in the water column, not hunting.

I pulled them all out and put them in the holding tank. Dumped the larval tank and cleaned it. By then there were 20 dead and 30 still alive. I put the live larvae back into the larval tank with new food and headed to Waikiki to get more water. When I got home there were only 2 survivors left.

I wondered if an external parasite had been introduced with the wild plankton but could not find any evidence of that. I treated the remaining two larvae with antibiotics in an effort to learn something. Tonight I can only see one live larva left. How can one larva survive when 49 died today?

I wasn't expecting this but that is the nature of the beast. The good news is that I learned a lot from this larval run. I've also got the cultured feeds in good shape so we should have a quick turn around time.

Here is a photo to show the size of the larvae at day 24. The average body size was 4.5 mm and total length was 6 mm (the tail is clear and difficult to see in the photo).

Here is a close up of the scales starting to form. those arrow like points in between the black dots on the skin of the larva are the beginnings of scales.
Note also the dark pigmented line running through the dorsal fin. That indicates the larvae are close to settlement. (Which makes this loss even more of a bummer!)

Please keep your fingers crossed for more fertile eggs!

Saturday, October 26, 2013

Ups and Downs... and Ups

The P. venusta larvae gave me a little trouble this week.

I've been counting larvae every day and the number that I could see in the tank was always somewhere around 23 larvae so I was estimating I had 30 larvae. Several days ago when siphoning the tank I sucked up 5 dead larvae, and still counted 23. The next siphoning, I sucked up 5 dead larvae again, and again still counted 23 larvae. The live larvae did not look 100% good to me and I started to worry about the deaths. I went to check the tank and with the water a little clearer than normal and I saw 10 dead larvae on the bottom! So I did what any professional larval culturist would do and I FREAKED OUT!!

I slowly scooped out each larva into a holding tank. Then dumped and cleaned the larval tank and carefully moved all the larvae back in one by one. I felt like I might lose all the larvae by handling them this way but I also knew I would lose them if I didn't make a change.

In moving the larvae I counted 58 and only one died the next day.  :)

Here's a video taken today of a 20 day old P. venusata.

If you have difficulty watching the video here, try it here

Sunday, October 20, 2013

Day 14 P. venusta video

Here is a link to a video I took this afternoon. It's taken with a point and shoot camera so the focus goes in and out as the larvae swim by but you can get a good look at how they are developing. The larvae were messin' with me and as soon as I'd get myself together on one side of the tank they would go to the other side. I think I went back and forth at least ten times and this is what I got for my efforts!
At least there are glimpses in focus.

Friday, October 18, 2013

Day 11 for the P. venusta

Today is day 11 post hatch and the P. venusta larvae are still looking strong and developing well.
I had to be brave today. I've been changing water daily but have not siphoned the bottom for fear of sucking up larvae since I can't see a thing down there in the darkness. Got a good cleaning done today and only sucked up 4 larvae which were in good shape and returned to the larval tank.

Here is a photo of one of the larvae at day 11. This larva was 4 mm in total length which is now too large for photos on the compound scope so here is an anterior photo followed by a posterior photo.

The larvae are still being fed a combination of cultured copepods and wild plankton and we will be shifting to more cultured feeds since we've had some thunder storms with rain that have resulted in an algae bloom in Kaneohe Bay where I collect the plankton.

Monday, October 14, 2013

So Far So Good with P. venusta

Today is day 8 for the P. venusta larvae and they're doing well. Because I have a dark floor on the tank I cannot see the deeper larvae and I have no clue how many we have left. There are definitely quite a few less than we started with and that is expected. I am happy with the numbers I am seeing and not being able to get a good count just makes things difficult in terms of collecting data.

The following photos were taken yesterday at day 7.

Most of the larvae are fairly uniform in their development. When viewed from the top the gut is plump and the larvae are looking strong. Here is a larva viewed from the side. Notice the pink/red hue which is the vascular development at 40x.

Here is a closer look at 100x of the vascular development, (the red veins).

I always like to check the gut and here is a nice plump tummy.

Here is the gut at 100x and you can make out some semi digested copepod body parts.

The larvae are certainly feeding well and yesterday I had to add 117,150 food items which consisted of both cultured copepods and wild caught plankton.

Monday, October 7, 2013

Paracentropyge venusta again

Eggs collected last night from the venusta tank were fertile so I started the next larval run this afternoon with the eggs just before they hatched.
Here is a photo of an egg 15 hours after spawn and an hour before hatching.

Saturday, October 5, 2013

Behavior issues

I have to say that the P. venusta larvae died due to their behavior. Not bad behavior, but different behavior which I was not prepared for. These larvae like to sit on the bottom and I have not seen that in other larvae that I've worked with. Normally I clean the bottom of the larval tank on a regular basis but could not do so while they were sitting there. They were strong and fed well and I had plenty of food to offer but could not clean up after them well enough to keep water quality up. So I have made some changes to the larval rearing tank for the next run. Basically darkening the bottom and brightening the surface to see if that will help keep them off the bottom. I did have the opportunity with two small spawns to test if the larvae are attracted to light and they do seem to be which is why I am going with a darkened tank bottom on the next run.