Table 1. Stress signs on fish observed during the CuO NPs exposure.
| Tank | Day | Stress sign | n | % | Intensity |
| FW0.5 | 6 | Loss of buoyancy/swimming control | 2 | 16.7 | Mild |
| FW5 | 5 | Late response to feeding | 4 | 33.3 | Mild |
| 6 | Loss of buoyancy/swimming control | 1 | 8.3 | Mild | |
| 7 | Late response to feeding | 5 | 41.7 | Mild | |
| SW0 | 5 | Loss of buoyancy/swimming control | 1 | 8.3 | Mild |
| SW0.5 | 5 | Loss of buoyancy/swimming control | 2 | 16.7 | Mild |
| SW5 | 5 | Loss of buoyancy/swimming control | 2 | 16.7 | Mild |
| 7 | Late response to feeding | 4 | 33.3 | Mild |
n: number of animals per tank showing the stress sign (the percentage of stressed animals is also shown). Intensity: represents at what extent the observed stress signs affected the normal behavior of the animals.