Larval Rearing

Larval Rearing-Step by Step

Since P. fridmani eggs will hatch after only 4 days the larvae will be much smaller than clownfish larvae. (Think 5mm slivers of glass with 2 shiney eyes.) The larvae need to be fed rotifers as early the next morning as possible.

Step One: Incubation Choices

While it is best to allow the male to incubate the egg mass, some males may take a while to learn how to do that. If the male has problems tending to the egg mass you can incubate the eggs artificially in an "egg tumbler". Basically a glass funnel with an airline to provide bubbles to keep the eggs moving and to avoid fungal infection. If you choose to use this method the egg mass should be dipped in a dilution of formalin to help control fungal problems.

After disinfection the eggs mass can be placed in the tumbler.

Egg Tumbler: A simple egg tumbler can be made with a glass funnel and airline tubing. I used a light reflector as a base to support the funnel. Eggs are placed in the tumbler and "tumbled" with air bubbles. It takes a bit of parctice to get the bubbles right, not to slow and not too fast. You just want to make sure that the eggs keep moving and don't get stuck.

To help keep the water warm I place the metal base on a reptile heating mat, you could also partially submerge the funnel in a tank with water and a heater.

Here is what mine looks like:

Step 2: Fourth Night

Artificial Incubation:

As I mentioned, the eggs should hatch on the fourth night after they were spawned. Since I'm not usually awake early enough in the morning, I've begun to add rotifers and phyto to the tumbler on the night of expected hatch so the larvae have something to feed on before I wake up. (That is why there is a slight green tint to the water in the above pics. This method has been working well for me.)

The first day after the eggs start to hatch I start transfering the larvae to the rearing tank.

This is what it looks like in action when the eggs hatch:

Parental Incubation:

Once the male gets to the point where he can incubate the eggs without eating them, you can pull them on the evening of the fourth day after the spawn. The egg mass is placed in the tumbler near a bright light. Since the eggs are only tumbled for a short time there is no need for the formalin bath. I'm having great results with this method.

About an hour after transfer to the tumbler with bright light. The bright light certainly gets them to pop! Halfway through the hatch I transfered at least 400 to the larval tank.

In this vid you can see how phototaxic they are. With the air off they all swarm toward the light.

Step 3: The Larval Tank

Larval Tank: A normal 10 gallon, half filled with water to start. Having the tank only half full allows you to maintain a high density of rotifers during the early stages. With advice from Witt, I place the heater on the side of the tank and put the airstone between it and the glass. This provides unidirectional water flow rather than the multidirectional flow that you would get with the airstone in the middle.

At this point, I've found that a 24hr lighting cycle is important as is heavy feeding with highly enriched rotifers. Using several types of phyto for the "greenwater" seems to help as well. I use a combination of Rotifer Diet HD/IA from Reed Mariculture as well as live Nannochloropsis. (Pros and cons between live and non-live phyto will be discussed on another page and you can decide what works better for you.) Rotifers are the main food source until about day 9 when newly hatched Artemia are added to the diet. If possible, copepods can be added around day 15 to help the larvae make it throught the metamorphosis period.

Hint: I've found that when using IA there will be a bit of a detritus build up on the bottom of the larval tank that needs to be siphoned out regularly. Doing so can present problems as some of the larvae can be siphoned out as well.

To avoid that, I first siphon the bottom with a length of rigid airline tubing attached to a length of flexible tubing. It is important to keep the rigid tubing on the bottom of the tank, this lowers the risk of siphoning out the larvae. Since the tubing is small in diameter it can take a little while to siphon out all of the detritus, be patient.

After all the detritus is removed I then siphon out more water (about 20% total) using a larger diameter length of tubing that has a piece of 120 micron mesh attached to the end. This keeps the larvae in the tank but allows for a quicker water change.

Hint: When doing the water change using a white bucket helps one to see any larvae that may have been siphoned out. They are very hard to see in an orange Home Depot bucket. I find it best to check for them before using the larger tubing by simply letting the detritus settle for a minute and then shinning a flashlight into the bucket. If you wait until after the total water change there is too much water in the bucket and the larvae are difficult to spot.

I recently discovered a great way to locate larvae that have been siphoned out accidentally. Simply shine a bright flashlight against the outside of the white bucket, the larvae will be attracted to the light and are easy to get out. Note: This only seems to work up until about day 14 post hatch, they seem to be a little smarter by then and if you don't catch them on the first try they wise up and avoid the light. They are also better at avoiding the siphon so fewer should end up in the bucket.

Larval Development

I recently purchased a microscope that gets some pretty good images so I've been been getting pics of a larvae each day post hatch.

1 hr Post Hatch