Published two weeks ago in 2009 in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers made an interesting find: the addition of a specific strain of probiotic bacteria to larval clownfish food and tank water immediately post-hatch yields fish with increased body weight, decreased metamorphosis time, decreased stress markers, and reduced bone deformities.  If you are a fish breeder, this is very interesting news indeed!

What the researchers from the Universitá Politecnica delle Marche, Ancona, Italy, did was to test a specific probiotic bacteria, Lactobacillus rhamnosus IMC 501, in conjunction with newly hatched false percula clownfish, Amphiprion ocellaris. They setup a Control group that did not receive probiotics, a group that obtained L. rhamnosus exclusively through their food, and a group that obtained the bacteria through their food and dosed into their tank water.  The results were surprising and showed that the best results were when L. rhamnosus was obtained from both their rotifer food source and dosed into their tank water. According to their paper, this is the first investigation into understanding how probiotic bacteria affect larval fish development.

The following benefits were found with the combination of L. rhamnosus in their food and tank water immediatey post-hatch:

• “twofold higher body weight in both clownfish larvae and juveniles when probiotics were supplied via live prey and added to the rearing water”
• “development was accelerated with metamorphosis occurring 3 days earlier in fingerlings treated with probiotic”
• “significantly increased gene expression of factors involved in growth and development”
• “probiotic treatment lessened the severity of the general stress response”
• “an improvement of skeletal head development was observed, with a 10-20% reduction in deformities for juveniles treated with probiotic”

If you are a fish breeder, I would definitely look into probiotic treatment of your fish larvae immediately post-hatch as its effects are significant.  The paper is open-access, so anyone can read it for free and it is also available as a PDF as well.