Yeah, old habits die hard. Everyone has to find one’s own way (and time schedule) to change them :-)

There’s a lot of research in that respect. Some food for thought:

https://www.pbs.org/wgbh/nova/article/fish-have-feelings-too/

https://www.psychologytoday.com/us/blog/animal-emotions/201406/fish-are-sentient-and-emotional-beings-and-clearly-feel-pain

I no longer Steal from Nature

You are diseased in understanding and religion.
Come to me, that you may hear something of sound truth.
Do not unjustly eat fish the water has given up,
And do not desire as food the flesh of slaughtered animals,
Or the white milk of mothers who intended its pure draught
for their young, not noble ladies.
And do not grieve the unsuspecting birds by taking eggs;
for injustice is the worst of crimes.
And spare the honey which the bees get industriously
from the flowers of fragrant plants;
For they did not store it that it might belong to others,
Nor did they gather it for bounty and gifts.
I washed my hands of all this; and wish that I
Perceived my way before my hair went gray!

Al-Ma’arri (973-1057)