One thing that helps me deciding which fish is possibly biting, along the tug animation, is to count how long it takes for it to bite. For example certain fish bites in a few seconds where some take 10+ seconds. When I went after Anomalocaris, big fish in Coerthas Central Highlands, it required a mooch fish which would bite quite soon, so if it took longer than what I had counted, I just cancelled that cast and went for it again. That limited my fish yield to two possibilities since third and fourth (if I recall correctly) took way too long to bite.

Perhaps that'll help with the Ala Mhigan Ribbon. I haven't gotten to try that fish yet myself.