Fluorescein: a rapid, sensitive, nonlethal method for detecting skin ulceration in fish

Area of Science:

• Aquatic Animal Health
• Veterinary Diagnostics
• Fish Biology

Background:

• Assessing fish health requires simple, rapid, and accurate diagnostic methods.
• Existing methods may not detect subtle or early-stage skin lesions in fish populations.

Purpose of the Study:

• To evaluate the efficacy of fluorescein dye as a rapid diagnostic tool for detecting skin ulcers in fish.
• To determine the sensitivity and safety of fluorescein for identifying subclinical lesions.

Main Methods:

• Administered fluorescein dye solution (0.10 mg/mL for 3 minutes) to various fish species, including rainbow trout, channel catfish, goldfish, and hybrid striped bass.
• Examined fish for the presence of skin lesions, comparing fluorescein-detected ulcers with naked-eye observations.
• Assessed the impact of high fluorescein concentrations on fish health and survival.

Main Results:

• Fluorescein rapidly and effectively detected experimentally induced skin ulcers, including pinpoint lesions invisible to the naked eye.
• Lesions were clearly demarcated after fluorescein treatment across all tested fish species.
• Subclinical ulcerations were frequently identified in fish appearing clinically normal, suggesting potential prevalence of skin damage.

Conclusions:

• Fluorescein is a highly useful, non-toxic tool for the rapid screening of skin ulcerations in diverse fish populations.
• The dye aids in identifying subtle or subclinical lesions, improving fish health surveillance.
• Fluorescein application at tested concentrations did not adversely affect fish health or survival.