Poor a. melanopus hatch rate

[jaybro]

I have a young pair of a. melanopus that started spawning about 3 months back. The nest size grew nicely from the earlier meager nests to the current 200ish eggs laid. The clowns are spawning every 11 days, the clutches hatch 8 days from being laid.

I have many 'pairs' of clownfish all on this same system/water volume, 5 that spawn (3 of those regularly) and all their hatch rates are very high. However, this melanopus pair is having a horrible hatch rate. Specifics below...

The following is a specific example, but this is how most of the hatches go. Out of roughly 180 eggs in the last batch, roughly 50% of the eggs were thinned by the parents which seems awful high. On the night of hatch, only 10 hatched. I've tried leaving the remaining to aeration, and I've tried replacing the eggs for the next day with the parents who luckily go right back to tending them. Either way, on the night following hatch, no new hatches occur and by the following morning the eggs have died. The eggs that do hatch have survival rate between 80 and 90% so the larvae that hatch seem strong enough.

My first thought was diet. I tried experimenting both with the quantity of shrimp based food they were getting (though I've had no problem with the eggs coming unattached) and increasing the percentage of beefheart I'm feeding them. I've not seen a bit of difference with any diet changes for the parents, either positive or negative. My general feeding regmin for active broodstock is :

Morning -- flake mix of 50% beefheart flake and 50% spirulina flake
Afternoon -- frozen choice of day, usually mysis
Evening -- home mix of fish, oysters, prawns with shells, beefheart and cyclops-eez.

The also often get a 4th 'random' feeding during the day, but this varies greatly.

I've tried antifungal treatments for the eggs, but I don't THINK that is the problem (it might be, but I received no difference with antifungal treatments, and none of the nests from other pairs in the same water volume have the same problems.)

What else would folks suggest trying? Do you think this might be due just to the young age of this pair and they may outgrow it? (I thought perhaps they were generating too many eggs for their size/age and consequently perhaps the eggs were weak. However I have no other melanopus to compare them too. The nest size seems fine for any other pairs I've experience in the same size/age category).

Please let me know if anyone has any thoughts/ideas or if I've neglected to include any relevant information.

A quick note on hatch tank preperation... 4 days before hatch I start a 10g tank by filling 100% with water, add a good starter culture of rots and feed IA daily. The night of hatch I pull out 90% of the water (through a rotifer filter) leaving the rotifers in the tank. I then refill up to about 60% which gives a very nice rotifer density (sorry, no specifics on density, I measure by eyeball what seems right, but this shouldn't effect hatch regardless!)

[Vert20]

I think it was in Wilkerson's book that I read the A. melanopus have had a very low hatch/survival rate among her pairs...she lists P. biaculeatus and A. melanopus as two of the three hardest to raise.

I am pretty sure she cited low hatch rate and egg survival as the norm just as you have experienced.

My pair has started cleaning after 2.5 years so I am hopeful I can add to the melanopus experience sometime this year.