Issue Date
2025
Abstract
The 17α-methyltestosterone (MT) is a synthetic androgen widely applied in aquaculture, particularly in fish species like Betta splendens, where males have higher commercial value. While MT is effective for sex reversal, the broader physiological and behavioral consequences of MT exposure remain insufficiently characterized. This study evaluated toxicological, behavioral, and morphometric endpoints in B. splendens to provide an integrated assessment of the impacts of MT exposure. Immersion assays in fry (2 days post- hatch, dph) demonstrated clear dose- and exposure-dependent toxicity, with cumulative toxicity under continuous 48 h immersion while greater tolerance under discrete immersion (two 3 h immersion at 2 and 5 dph). The 48 h LC50 was estimated at 138 μg/L under continuous immersion and 999 μg/L under discrete immersion, confirming elevated risk with prolonged exposure and practical relevance of the discrete LC50 to short-bath aquaculture use. Moreover, behavioral assays in juveniles (40 dph) and adults (90 dph) suggest endocrine disruption as MT immersion induced precocious bubble nesting across sexes and altered aggression patterns. Aggression was quantified using a mirror-induced assay based on latency to initiate displays, display activity (frequency/duration), and escalation frequency. MT elicited sex-specific alterations in aggression, delaying initiation in males while accelerating in females; both, however, showed heightened display activity and diminished escalation, reflecting a shift toward ritualized, non-contact aggression. Morphometric analysis showed that MT could suppress natural sexual dimorphism. Control juveniles (40 dph) displayed early fin trait differences between males and females, whereas MT-treated fish showed no significant sex-based difference in anal fin length, indicating reduced sexual dimorphism. Taken together, these results show that MT affects not only survival, but also key morphological and behavioral traits linked to reproduction. Sublethal changes in morphology and behavior may compromise reproductive ecology even when survival and growth remain unaffected, raising concerns over its continued use in aquaculture.
Source or Periodical Title
UP Los Baños Journal
ISSN
0117-1461
Volume
23
Issue
1
Page
52-67
Document Type
Article
College
College of Arts and Sciences (CAS)
Recommended Citation
Felipe, Imee Rose E.; Rosario, Alexandra May R.; and Tuason, Vijay Hanz A., "Broader consequences of 17α-methyltestosterone-induced masculinization in betta splendens: toxicological, behavioral, and morphometric outcomes" (2025). Journal Article. 6497.
https://www.ukdr.uplb.edu.ph/journal-articles/6497