One way to select high-quality shrimp fry is by ensuring their health. Common tests for assessing fry health include the bolitas test and Polymerase Chain Reaction (PCR). This article covers the bolitas and PCR tests as essential steps in fry selection and summarizes findings from recent studies.

What Is Shrimp Bolitas and Its Effects?

According to Intriago (2024), several hatcheries in Latin America experienced up to 90% mass mortality in zoea II-stage fry in September 2023, attributed to a common feature: the presence of bolitas in the fry. The term "shrimp bolitas" refers to a physiological abnormality—small rounded deposits in the hepatopancreatic tract, consisting of detached epithelial cells. This bolitas presence indicates damage to hepatopancreatic tissue, negatively affecting shrimp health. Research shows bolitas are often accompanied by swelling of the hepatopancreas, which disrupts digestive functions.

Shrimp with bolitas display symptoms such as loss of appetite, altered swimming behavior, lethargy, and ultimately death. Bolitas testing has become a standard health assessment before stocking shrimp fry. Bolitas can appear in two areas in fry: hepatopancreatic bolitas (BHP) and gut bolitas (BGI). Typically, fry completely free of bolitas are preferred for farming, while those with 50% or higher bolitas content are considered unsuitable.

PCR Testing in Shrimp Fry Selection PCR testing identifies specific genetic material within shrimp fry, including pathogens, at a molecular level. Real-time PCR, or qPCR, is commonly used, offering graphical identification data for more precise analysis. Quality shrimp fry often carry certificates such as Specific Pathogen Free (SPF) or Specific Pathogen Resistant (SPR). However, PCR testing remains necessary to confirm freedom from various pathogen strains.

Accuracy of Real-Time PCR Compared to the Bolitas Test While the bolitas test is commonly used, it has limitations in reflecting overall fry health. Bolitas testing detects fry with potentially poor growth prospects through physiological observation but cannot identify specific pathogens. Intriago (2024) found bolitas in shrimp often correlate with Vibrio species and Rickettsia-like Bacteria (RLB) in surrounding water. Despite this connection, the bolitas test cannot accurately validate pathogens within fry, whereas Real-Time PCR provides specific identification and detection of various shrimp diseases.

Specific & Accurate Detection

with qPCR qPCR’s molecular-level accuracy enables precise detection of pathogen types and abundance, providing a quality benchmark for shrimp before pathogens infect and cause symptoms. This allows farmers to select fry from hatcheries more comprehensively.

Multitarget Detection

PCR testing also identifies multiple pathogens in fry samples, unlike the limited pathogen indication in bolitas testing. Although bolitas testing remains a useful physiological health reference, pathogen type and abundance validation in fry require PCR.

Accurate Shrimp Disease Screening with CeKolam

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Sources:

• Hang Tuah University Article
• IOP Science Article
• PMC Article**