The blue dye makes the fish’s red blood cells shrink and get wrinkled, which probably stops them from carrying oxygen properly.
Scientific Claim
Exposure to sub-lethal methylene blue causes visible structural damage to red blood cells in Labeo rohita, including crenation and membrane shrinkage, which are linked to declining hemoglobin levels and oxidative stress.
Original Statement
“RBCs exhibited crenation and membrane shrinkage”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The claim describes an observed morphological change without implying causation. The verb 'causes' in the claim is slightly strong, but the structure is observational and the effect is directly reported.
More Accurate Statement
“Exposure to sub-lethal methylene blue is associated with visible structural damage to red blood cells in Labeo rohita, including crenation and membrane shrinkage, which coincide with declining hemoglobin levels and oxidative stress.”
Evidence from Studies
Supporting (1)
The study found that a low dose of methylene blue made the fish’s red blood cells shrink and get wrinkled, while also lowering their blood’s oxygen-carrying capacity and causing cellular damage from stress—exactly what the claim says.