Thursday, June 25, 2015

larval Nemo hunting

For the past several years I've been giving clownfish eggs to a group at the University of Hawaii who are studying how larval fish learn to catch their prey.   The research group has gotten some cool video footage and I thought some of you might like to see it. Here's a short clip of a 12 day old clownish hunting an adult calanoid copepod.

Reminds me more of a grouper than a clownfish larva!

Tuesday, June 9, 2015

An Interesting Surprise

While I'm waiting for fertile eggs from the fish that I'd like to raise and in an effort to continue the learning process and improve larval rearing methods, I started a small larval run using G. personatus eggs. I had seen some spawning behavior from the young bandit angelfish,  A. arcuatus which live with the personatus and I had hoped that the eggs I had collected might be those of the bandits. As I got further along into the rearing run I could see that these were personatus larvae. As the larvae approached the 35 day mark, some looked slightly different with darker than normal dorsal spines. The surprise came as the larvae began to settle out into their juvenile colors. Five of the larvae showed some black pigment where the body would normally be white.

Here's a photo of a day 45 larva changing into it's juvenile colors and sporting the extra black. Normally that posterior area of black would be white. I was very excited and intrigued by this. I sent this photo and the videos around  hoping to get some information as to what could cause this. So far the main consensus is that possibly something different in the larval rearing environment may have caused it. I didn't change anything intentionally but there are always many variables at play through the larval period especially when using wild plankton.

Here is a video of that same fish at 49 days old. (It's the fish with the black caudal and black on the dorsal and anal fins.)

Here is a video at day 52 and you can see that the fish with the black caudal has lost the black on the dorsal and there is just a smudge on it's anal fin.

Today, at day 60, only the caudal remains black. That is a normal marking on a juvenile personatus however that black caudal doesn't normally show up until approximately 6 months of age (in my experience rearing this species). The other four fish that had extra black markings all currently look like normal G. personatus. I have the black caudal fish separated so that I can follow it's development and I'll keep you posted if anything changes.

I just love larval rearing surprises!!

Wednesday, June 3, 2015

Coming of Age

The three tiny Bandit Angelfish that Rufus gave to me two years ago are coming of age.

Over the last year they have developed into a larger, a not as large and a smaller sized fish. I had assumed from the start that I would end up with a male and two females. In my experience, the males have a somewhat sunken abdominal area and the females are plump in that area of the body.  At the beginning of this year I noticed that the two larger fish both had the sunken appearance of a male and I thought that this was odd. About three months ago the two larger fish began to fight. This was serious fighting with the ripping of fins and bodily contact. I put my fish trap in the tank in an effort to catch one of them. It didn't matter to me which one, I just wanted the fighting to stop. I didn't try to move the rocks and catch them with nets since they share their tank with the G. personatus pair and I wasn't going to freak the personatus out and risk damaging them. Neither of the fighting bandits would enter the trap and the fighting escalated for several days. All they did was chase and fight. Their respiration was constantly high while they overexerted themselves and they began to lose weight. I prepared to take the tank apart hoping that the personatus pair would deal with the intrusion in a mellow manner. Then suddenly the fighting stopped and the hierarchy was established. The larger bandit started to court the smallest and the odd man out middle sized fish would just cruise around as if not interested. Life settled back down and I started collecting eggs from these new bandit spawns but all have been infertile.

This week the Bruce Jenner story "call me Caitlyn", of his transformation from male to female has been all over the news. Last night the "odd man out bandit" suddenly, out of nowhere, makes the move to become a female and as the pair was spawning he dives right into the middle of it pushing the female out of the way and fluttered in front of the male. The larger male continued on and spawned with both fish although no eggs were produced. The tank that these fish are in is located opposite the television and I can't help but wonder if that sex changing bandit was watching the news and realized he still had options.

Today the fighting has begun again. This time between the small female and the new female. The smaller is about half the size of the new female and is standing her ground. Posturing and then hiding only to run out and nip the tail of the new female as she swims by the hiding hole. It is both worrisome and hilarious to watch and I just hope they can work it out before I have to take the tank apart and catch one of them. Hopefully all of these shenanigans will lead to fertile eggs!

Here's a photo of our new sassy female, Caitlyn.