Data from: Dietary supplementation with Ocimum gratissimum essential oil increases intestinal mucosal fold height, but not growth, in Hypostomus johnii

Individual fish data from a 60-day feeding trial with armoured catfish (Hypostomus johnii) juveniles fed a commercial diet supplemented with 0 (control), 0.5, 1.0 or 1.5 mL of Ocimum gratissimum essential oil per kg of diet. The trial used a randomized complete block design with three weight-class blocks (R1, small; R2, medium; R3, large), one 150-L tank per treatment in each block, and six fish per tank, in a recirculating system (Chapadinha, Maranhão, Brazil; January–March 2022). The Excel file contains: README (variable definitions, units and formulas); Growth (weight and total length of each fish at days 0, 30 and 60, with weight gain, specific growth rate and condition factor); HSI (body and liver weight, two fish per tank); MFH (intestinal mucosal fold height, mean of 10 folds per fish); Survival (per tank); Mortality (date, tank, weight and length of fish found dead); and Water_quality (daily temperature and periodic dissolved oxygen, pH and ammonia). Plasma biochemistry is reported as tank means in the associated article; individual values are not available.