There are many vegans who do not enjoy eating fish, eggs and shellfish because they feel the fish is cruel and inhumane. The reason for this feeling is that most of the fish are raised in an environment that is not even remotely suitable for them to live in, so they do not have much of a choice but to eat meat. If you are a vegan and are in the position of having to try and avoid eating fish, I think this is something that should be considered for your sake alone and you should also consider the fact that there are many other types of fish that you could eat in their stead. You can find plenty of delicious and nutritious fish recipes online and you will find that many of these recipes are actually vegan as well.
It is quite common for vegans to have a difficult time trying to incorporate the vegan diets into their everyday lives because of the difficulty they feel in making the transition from one eating habit to another. If you feel that this will affect you then I would suggest that you try and change eating habits one at a time so that you can be sure that you will be able to adjust to the new eating habits. You will find that once you have started eating a vegan diet, you will find that you have a lot more energy and you will be able to enjoy a healthier life because of it.