Probiotics Helped Amputated Fish Fin Grow Back Thicker

This Zebrafish study was published on May 16th, 2022 by scientists from the Department of Life & Environmental Sciences and Biostructures and Biosystems National Institute in Italy. They claimed that one of the proven benefits of probiotics was the potential for bone mineralization according to Morphological analysis but that bone regeneration was less studied and not yet proven. 

In a previous post, I wrote about how studies on Zebra Fish fed with Lactobacillus Plantarum showed benefits for anxiety. Zebra Fish is a popular animal for probiotic studies for several reasons. The zebrafish caudal fin, in particular, is great for live tracking, fin accessibility, and importantly the absence of detrimental effects on the amputated fish according to at least one study.

Once the caudal fin is amputated the zebrafish is said to be able to regenerate the fin by creating lineage-restricted blastemal cells. Another study even showed that the Zebrafish was even able to regenerate its own heart after amputation.


Prior to having their Caudal Fin amputated the Zerba fish were preconditioned with probiotics that contained the following at 106 CFU/ml for 14-days.

  • Bacillus Subtilis
  • Bacillus Licheniformis
  • Bacillus Coagulans
  • Lactobacillus acidophilus 
  • Saccharomyces cerevisiae (Yeast)

They were particularly interested in the Bacillus Subtilis strain because of its ability to produce Vitamin K or Menaquinones. The control group of Zebrafish was simply fed a standard diet consisting of Zebrafeed twice per day.



The fins were recorded at the pre-amputation stage, immediately after post-amputation, then at 1, 5, and finally 10 days post-amputation. The measurements taken weren't as simple as measuring the total length and leaving it at that.

Dotted line tracing was used for fin ray width, stump width, peduncle width, and segment length. Statistical analysis of regeneration rate was used between probiotic / control groups and so were various morphometric parameters.

Compared to the control group, Final size parameter was 8–9% higher in probiotic treated fish at the final 10-day mark. Most of the size came from the width and it was noted that the probiotic fish "had thicker fin rays".

Once the amputated area had regrown, the control group fish switched back to isometric growth but the probiotic fish maintained an allometric growth pattern despite recovering the amputated part of the fin.

It's thought that this was a result of the probiotic bacteria being a major vitamin K2 producer. While it's clear probiotics aren't a miracle magic cure for amputees, the study concluded that "probiotics can be a potential prophylactic candidate to improve bone health.".

Reference: Sojan, J.M., Gioacchini, G., Giorgini, E. et al. Zebrafish caudal fin as a model to investigate the role of probiotics in bone regeneration. Sci Rep 12, 8057 (2022).

1st Fish Graphic Created By Author.

2nd Fish Fin Photo's Taken From Study Paper.