Clownfish fry growth rates by species?

Do different species of clownfish fry have significantly different growth rates? Or do environmental factors have more of an effect?
 
My Spotcinctus clowns seems to be growing very slowly (at least to me). They are about 3.5 months old and most are about 1/2". I just saw a friends mocha ocellaris fry that are a few weeks younger and they are 2 - 3 times the mass of my fry. So does the clarkii complex grow slower or am I doing something to prevent faster growth?
 
Also of note, my broodstock started spawning at about 1.5 years of age. They obviously started young and still have a quite a bit of growing to do themselves. I let the first two batches go and then the 3rd batch all died in my first attempt at raising them. The fourth batch is the first one I was successful with and is the batch in question. The larva seem smaller than I expect when they hatch and I have yet to see any signs of a yolk sac. I tend to loose 50 - 70% of the larva the first night. So I wonder if young broodstock with potentially weaker larva could also be a contributing factor.
 
The BRT (25 gallon) is kept at 81 degrees and the clowns are fed 3 - 5 times a day with Chromaboost TDO and now occasionally with Reef Caviar. They have been raised in a salinity of 1.025 since it is more convenient when I am making water for all of my other reef tanks. Could the salinity at the level be the cause of slower growth? I did see some reports that showed highest growth rates at 1.015 - 1.020 depending on the report.
 
Or am I just an impatient first time breeder that is anxious to sell his first clowns and make room for even more in this addicting hobby?
 
Any thoughts or comments would be appreciated.
 
Lee

I grow bicintus aswell at 10 months most are about 3 to 3.5 inches while some are smaller .Nitrates have been show to inhibit thyroid  function in some fish.