I would like to start this off by reassuring--I don’t mean to start drama with this but I very strongly disagree with your position and I want to open up a discussion and address it, and articulate why I disagree (since I see other people have also disagreed).
Regarding the tail damage your betta has: The curling appearance of your betta’s tail along with the presence of red streaking (neither of which are present in prior pictures of this betta, I scrolled through your blog to look) makes me question your assessment that this is a case of fin biting alone.
Regarding your separation anxiety idea: I honestly think that your evidence is too weak to actually support it. (Not to say that fish don’t experience separation anxiety, I just don’t think your observations support it.)
I agree with some of your methods for treating fin biting behaviors as per this post (namely the techniques that involve distraction, increased stimulation, and de-stressing). Those are tried and true methods to decrease fin biting, generally accepted by betta keeping communities because they prove to work. Given that tail-biting is a behavior that is seen in fish that need more stimulation (or have heavy fins causing physical stress), it makes sense that increased enrichment & decreased stress will help stop that behavior.
Take for instance, a totally different animal--an Ecuadorian hermit crab (which by definition, cannot be domesticated--land hermit crabs very, very rarely reproduce in captivity and only in very specific careful recreations of their normal habitats). Eccies are known to climb around their enclosures and be very very active--an Eccie that has ropes, ladders, and climbing materials will be more engaged with its environment, whereas an Eccie with no other climbing outlets will climb the sealant of the tank and try to make a break through the lid. If a human picks an Eccie up, it might climb all over and up and down on the human. This doesn’t mean it likes the human, or that when it’s alone it’s trying to get closer to its human--it just means that the Ecuadorian hermit crab requires environmental stimulation to redirect behaviors, and deriving any other meaning from that is anthropomorphizing.
So in your case--maybe you are just providing the right kind of stimulation that your fish need to be happy and not participate in tail-biting behaviors.
In addition, when it comes to your evidence for each treatment--You have used multiple treatments on the same fish, so who is to say that a treatment like “keeping goodbyes short” (like with Duo) is what’s having the positive influence on your fish, when you are also providing additional environmental stimulation with videos? Or maybe part of the goodbye, which is providing food, is also providing stimulation in terms of a prey-catching need?
Additional evidence you provide, such as “they change color”, doesn’t really support your theory either--what does the color change mean? Do they lose color every single time you leave the house? Have you observed your fish when you aren’t home to see them, such as via a webcam, to see if the color change is something that is consistent all day while you are not there?
You also cite enthusiastic greetings, attentiveness to your presence, and reluctance to interact with other people that are not you--all of these could easily be explained by the fact that they associate you with both food & additional environmental stimulation, causing them to be more interested in you.
And perhaps the only reason you have never seen your betta fish bite its tail is because when you are in the room observing, you are providing a distraction and environmental enrichment just by being there. You’d be hard pressed to find an owner who has actually witnessed a betta bite its own tail (I think the only time I’ve heard of that, the betta was totally blind).
I’m also going to quote one of your reblogs:
“No, there is no scientific evidence to support my claim and yes, it probably sounds anthropomorphic to some people. But fish welfare and behavior research is years behind that of other animals right now. I understand the value of scientific evidence but at this moment, we don’t really have any either way, especially not in regards to domesticated fishes. All I have is my knowledge, my education, and my experiences with my own bettas. This provides more evidence to me to support the idea than it does to disprove it.”
I mean, you are anthropomorphizing your fish, there’s no way around that--interpreting your fish’s feelings and emotions as indicated by your own person views. Direct quote from you--“Maes has always really liked watching lightsaber fights,” How do you know? How does Maes indicates that he/she likes watching lightsaber fights--a more plausible answer is that the muted backgrounds with bright colors & flashing catch your betta’s attention, but to say that Maes likes the lightsabers is to assume something you cannot know, not with what we know now about fish behavior & conscience.
Just because we don’t have the answers backed up with science, does not mean that we can substitute personal anecdotes as scientific evidence. And just because there is no behavioral theory readily applicable to fish, does not mean that we can take other animal behaviors and extrapolate them to fish (especially when those behaviors are coming from mammals with very different brain structures and domestication histories).
I definitely think your personal anecdotes and observations on what treatments have been effective in reducing fin biting are quite useful, but I think that’s where it ends and your idea of separation anxiety just doesn’t hold up.
What I would really love to see, is people delving into the field of fish behavioral studies to answer questions like this--can fish experience separation anxiety?