# Investigation on parasitic infestation of Labeo rohita (Hamilton, 1822) in the south‐western region of Bangladesh

## TL;DR

This study examined parasitic infections in Rui fish in Bangladesh, finding six parasite types affecting their organs and stressing the need for control measures.

## Contribution

The study identifies six parasite categories in Labeo rohita and documents their impact on major organs in the Khulna region of Bangladesh.

## Key findings

- Six parasite categories were identified, predominantly in the intestines and liver of L. rohita.
- Histological changes were observed in organs like the liver, kidney, and gills due to parasitic infestation.
- The highest prevalence rate of parasites was recorded in March and May, with peak intensity in July.

## Abstract

Our investigation focused into Labeo rohita, commonly known as Rui, a freshwater aquatic species in Bangladesh. Despite their nutritional significance, these fish faced a pressing challenge: parasite infections threaten the economic stability of the aquaculture sector.

The present study aimed to investigate the parasite and histological changes in major organs of L. rohita, collected from Khulna region – Dumuria, Paikgacha and Rupsha.

About 180 (30/month) specimens were collected between the month of March and August 2023 to observe the parasitic status in L. rohita.

Through microscopic examination, a total of 323 parasites were uncovered, spanning categories including Cestode, Nematode, Acanthocephala, Trematode and Digenia, predominantly residing in the intestines of L. rohita. The highest prevalence rate (70%) was recorded in both March and May 2023, with peak mean intensity observed in July (3.73). Notably, the highest mean abundance (2.37) exhibited in July and index of infestation (45.34) in June. Histological analysis confirmed parasitic infestations in the gastrointestinal region, with displaying histological changes within major organs such as the liver, kidney, gills, spleen and testicles due to parasitic infection.

This study concluded that the indentified six categories of parasite and the affect of parasitic infestation in major organs of L. rohita within the study period. Urgent efforts to implement effective strategies for controlling the parasite infections in aquaculture to ensure the sustainable production of this invaluable fish species.

Over the study, 180 L. rohita specimens were examined,, revealing the presence of six distinct parasite species, consisting of endoparasites. Through microscopic examination, a total of 323 parasites were investigated, categories including Cestode, Nematode, Acanthocephala, Trematode and Digenia, predominantly residing in the intestines and liver of L. rohita.