I am looking to do a T4 assay in some mutant zebrafish who appear to show stunted growth. I am interested in observing whether treatment with T4 is going to have a positive effect and if these treated fish will eventually catch up with their wild type contemporaries. I am aware that zebrafish do not have distinct thyroid glands but rather tissue that is distributed in the body. I am looking for any existing protocols to do this as well as what might be the best way to monitor the hormonal effects on treated fish. Thank you in advance.