Swai fish (Pangasianodon hypophthalmus) is a freshwater species popular in global markets. Widely consumed for its mild flavor, flaky white flesh, and affordability, it serves as an accessible alternative to other white fish. Originating from the Mekong River basin in Southeast Asia, particularly Vietnam, it is also known as Vietnamese catfish or iridescent shark, though it is not a true shark. Swai fish are typically farmed in aquaculture settings and grow to a considerable size.
Swai Fish and Their Scales
Swai fish possess scales, though their characteristics often create a perception of being scaleless. Unlike many fish with prominent, visible scales, Swai scales are typically very small and deeply embedded in their skin. This embedded nature makes them less noticeable and not easily removable by hand, a common trait among catfish species. The Swai’s skin is often described as smooth, providing a protective layer against environmental factors and predators. These scales do not offer the same visible or tactile presence as those on fish like cod or salmon, contributing to their “scaleless” appearance commercially.
Swai Fish and Their Fins
Swai fish have a complete set of fins, essential for movement and stability in aquatic environments. They possess various types, each serving a distinct purpose. Swai have a dorsal fin on their back, a caudal (tail) fin for propulsion, and an anal fin positioned on the underside near the tail; paired pectoral and pelvic fins assist with steering, braking, and maintaining balance. These fins are typically dark grey or black, and in younger Swai, they can appear iridescent, contributing to their “iridescent shark” moniker. Their fin design enables effective navigation through water, whether in fast-flowing rivers or aquaculture ponds.
The Importance of Scales and Fins in Dietary Law
The presence of both scales and fins is a significant factor in certain religious dietary laws, notably Kashrut, the Jewish dietary laws. According to these traditions, as outlined in Leviticus 11:9-12, a fish must possess both fins and easily removable scales to be considered kosher. This requirement ensures that only specific types of aquatic life, considered “true fish,” are eaten, excluding creatures like shellfish or certain eels that lack these features.
The nature of Swai fish’s scales often raises questions regarding its kosher status. Because its scales are small, embedded, and not easily removable, Swai is often considered problematic under these stringent dietary guidelines. Many interpretations classify Swai fish as non-kosher due to the difficulty in verifying easily removable scales. Despite having fins, the ambiguity surrounding its scale characteristics typically leads to its exclusion from kosher diets, highlighting the precise definitions within these religious observances.