Abstract
Background:
The Mediterranean Sea has undergone significant ecological changes in recent decades, partly due to the introduction of non-native species. Lagocephalus sceleratus is an invasive Lessepsian species widely distributed in the Mediterranean, increasingly abundant along the Libyan coast, and potentially exposed to chronic environmental stressors. This species represents an important model for baseline pathological assessment in newly colonized marine environments.

Aim:
This study provides a descriptive histopathological assessment of kidney and gill tissues in adult L. sceleratus to document baseline tissue alterations without inferring direct environmental or pollution-related causation.

Methods:
A total of 150 adult specimens were collected from four Libyan coastal locations. Tissues were processed using standard histological techniques and evaluated semi-quantitatively (+, ++, +++) for lesion severity. Lesion severity grades were converted into ordinal numerical data and summarized using descriptive statistical approaches only.

Results:
Kidney tissues exhibited tubular degeneration, Bowman’s capsule dilatation, vascular congestion, extensive melanomacrophage centers (MMCs), and inflammatory lesions. Gill tissues showed disorganization of secondary lamellae, epithelial hyperplasia, edema, aneurysmal dilatations, vascular congestion, and MMC proliferation, some of which were associated with histologically observed parasitic structures.

Conclusion:
The observed alterations represent descriptive baseline tissue changes and should not be interpreted as direct evidence of pollution or specific environmental stressors. These findings provide reference data for future comparative pathological and ecological studies.

Key words: Lagocephalus sceleratus; Kidney; Gills; Histopathology; Melanomacrophage centers; Invasive species; Mediterranean Sea.