The quality attributes of filleted rainbow trout and Baltic herring in over-wrap packages (polystyrene or wood fibre), vacuum packages and gas packages (35% CO2+ 32·5% Ar + 32·5% N2, 35% CO2+ 65% Ar, or 40% CO2+ 60% N2) stored at 2 °C were compared. Mesophilic bacteria grew most quickly in over-wrap packed fillets and most slowly in vacuum and gas packed fillets. Coliform bacteria grew faster in over-wrap and vacuum packed fish than in gas packed fish. Over-wrapped herring fillets had the least drip formation during storage, whereas gas-packed herring had the greatest drip. Drip was very small in trout fillets in all package types. The appearance of herring was evaluated as worse in vacuum and gas packages due to the excessive drip formed. The odour of trout packed in a wood fibre package was evaluated as slightly poor at the very beginning of the storage due to the very strong odour of the package, which masked the odour of the fish. The sensory quality of both fillets deteriorated faster in over-wrap and vacuum packages than in gas packages. The sensory quality of trout and herring in the three types of gas packages was quite similar. Argon in the gas mixture did not increase the shelf-life of fillets.