Broodstock has the characteristics of a long breeding time, small breeding quantity, and a high economic value. At the same time, the broodstock is weak during the spawning period, which needs to be observed in time. Therefore, studying the behaviours of broodstock (chasing, spawning, aggregation, feeding, and swimming normally) could help fish farmers to understand the health status of broodstock and adjust breeding strategies in time. However, it is challenging to recognise these behaviours due to the high similarity between these behaviours. In this study, a camera’s infrared mode was used to obtain the behaviour recognition data in weak light conditions, and the visible light mode of the camera was used to obtain the data in sufficient lighting conditions. A Resnet50-LSTM based approach was proposed to recognise five standard behaviours. Due to the advantages of deep feature extraction, Resnet50 extracted the features of the input data in different dimensions through multiple convolution. These features were input into the Long-Short-Term-Memory (LSTM) classification model, enabling the extraction of time-series behavioural information Convolutional Block Attention Module (CBAM) was added after each stage in the Resnet50 network, which was able to focus on important features and suppress unnecessary noise interference. Meanwhile, mish activation function and ranger optimiser were used to improve the accuracy of behaviour recognition. 3925 videos containing 981,250 frames were collected and tested to compare the performance of the proposed algorithm. The test results showed that our method achieved a recognition accuracy of 98.52%. Additionally, we compared the test accuracy between the proposed method with eight competitive models, and the test results showed that the average recognition accuracy of the eight models was 95.04%, 97.32%, 97.18%, 97.52%, 98.32%, 77.80%, 85.10%, 90.8%, respectively. Our method shows higher average recognition accuracy. Overall, this is an effective method for intelligent aquaculture monitoring. The algorithm meets the needs of behaviour recognition, which has good robustness in an aquaculture environment and provides a new strategy for smart aquaculture.