Here are two articles on fish intelligence I've read recently, though the first is problematic in terms of writing (overblown results language in the title and first couple paragraphs) and in terms of non-ideal (cruel) experimental processes.  Watching fish suffocate alive on ice in a seafood store in Florida instigated my vegetarianism, actually.

Fish are sentient animals who form friendships and experience 'positive emotions', landmark study suggests

Fish can’t recognise faces if they’re upside down – just like us