Whenever I want to change to a different conda environment I can't remember the command to list all environments. However I know I can activate it with conda activate <env name> once I know the name.
When running just conda activate it tells me: You need to specify a conda environment. This is correct but also not very helpful. My suggestion would be to change the message to something like:
You need to specify a conda environment. To list environments use "conda env list". Even better would be of course to just print out directly the installed environments. This would probably needs some work and would be doing too much.