I had an icthy called Nikto. He was the first and the only sea creature i had for a very long time. One day i decided that i wanted to tame a basilo. I found it on the herb island. I was scared that the manta cult will kill nikto. But somehow when i attacked the mantas, they don't aggro. So i killed them all pretty easily. And then a megalodon spawned in. And they don't attack Nikto too. So long story short, i tamed the Basilo and were on my way back to base. When all of a sudden 5 megalodons attacked us. Not just that but 6 mantas joined in. Firstly im not scared since im on a basilo and a basilo is very tanky. But then the jellyfish came and stun nikto to death. I managed to kill all of them, but lost nikto :(
I found a couple ichthyosaurs and decided to tame one, then they all gathered up wanting food. It was annoying. I was taming a bunch of them, there was one that I kept feeding but it was loosing effect on taming; I left and got mad.
I’ve had many icthys. My first one was slaughtered along with my meg from a meg army. My second was shocked to death by eels when I tried to scrape a Leeds. My most recent is kept in a cage on passive for safety.