Preparation of gelatin feed and assessment of leaching. (A) The gelatin feed (containing Methylene Blue) was pipetted onto Parafilm in individually tailored morsels (1% body mass; shown here against a 1 US cent, 19.05 mm diameter) and allowed to set at −20°C. (B) Methylene Blue leaching over time at different gelatin concentrations with 4% w/v spirulina. (C) Methylene Blue leaching over time at different spirulina concentrations with 12% w/v gelatin. (D) Methylene Blue leaching over time using different solvents (12% w/v gelatin and 4% w/v spirulina). Data are means±s.e.m., n=6.

Eating of gelatin-based feed by fish. (A) Percentage of AB or TL fish from both sexes that ate the feed within 5 min of administration. (B) Time taken for AB or TL fish of each sex to eat the feed. Fish that did not eat the feed were excluded from time to eat analysis. Data are means±s.e.m., n=8 fish per strain/sex.

Behavioral effects of NMDA receptor antagonist administration. We measured the effect of MK-801 (4 mg kg⁻¹) administration 30 min prior to the novel tank test on activity and anxiety-like/predator-avoidance behaviors in AB fish of both sexes. (A) Bottom distance, (B) center distance and (C) distance traveled. Data are presented as box and whisker plots with the median (center line), interquartile range (box ends) and ±1.5 times the interquartile range (whiskers). *P<0.05 based on false discovery rate-corrected post hoc t-tests. Female vehicle: n=20, female MK-801: n=19, male vehicle: n=19, male MK-801: n=15.