It is the fact that, some people prefer not to consume any kind of fish or meat, as they believe that, being vegeterian has benefits for their health and also for the world as a whole. To a certain extend, I would agree with this opinion, but I think people should also consume meat or fish in a proportional portion. Thus, meat and fish contain rich ingredients and vitamins which are needed by human's body.
For the many reasons, people choose not to eat fish or meal. They act on the basis of scientific facts. Thus, meat and fish may cause different type of chronic diseases such as heart attack, cholesterol, cancer, obesity.
Moreover, demand on meat and fish is gradually increase. On this perspective, we would face negative problems that which may cause perpetual damages on our planet. Numerous types of fishes would extinct and it would make imbalance in the sea ecosystem.
On another aspect, being vegeterian is one of the ways to protest the policy of governments about slaughtering animals and fishes in order to avoid environmental issues.
However, another reason of no eating meat or fish is related some ethical values, which this communities prohibit to eat bıth of food sources for the such reason that, is inappropriate their certain values and rules. Somehow, they believe that, animals are just like the human being that should be respected as well as preserve their lives.
As consequence, It is reality that, being vegeterian has many utilities for our health and positive impact for environment. I agree with this approach. But, in my opinion, all species exist for each other. How the animals need each other for living, people also may consume the farm animals or fishes. Because we may obtain the certain types of nutrition from animals. But also, I believe that, if we keep the balance to consumption of meat, fish, vegetable, this would make our body more healthier than to become vegeterian. 
It is the fact that,  
some
  people
 prefer not to consume any kind of fish or  
meat
, as they believe that, being vegeterian has benefits for their health and  
also
 for the world as a whole. To a certain extend, I would  
agree
 with this opinion,  
but
 I  
think
  people
 should  
also
 consume  
meat
 or fish in a proportional portion.  
Thus
,  
meat
 and fish contain rich ingredients and vitamins which  
are needed
 by human's body.
For the  
many
 reasons,  
people
 choose not to eat fish or meal. They act on the basis of scientific facts.  
Thus
,  
meat
 and fish may cause  
different
 type of chronic diseases such as heart attack, cholesterol, cancer, obesity. 
Moreover
, demand on  
meat
 and fish is  
gradually
 increase. On this perspective, we would face  
negative
 problems that which may cause perpetual damages on our planet. Numerous types of fishes would extinct and it would  
make
 imbalance in the sea ecosystem.
On another aspect, being vegeterian is one of the ways to protest the policy of  
governments
 about slaughtering  
animals
 and fishes in order to avoid environmental issues. 
However
, another reason of no eating  
meat
 or fish  
is related
  some
 ethical values, which this communities prohibit to eat bıth of food sources for the such reason that, is inappropriate their certain values and  
rules
. Somehow, they believe that,  
animals
 are  
just
 like the human being that should  
be respected
  as well
 as preserve their  
lives
.
As consequence, It is reality that, being vegeterian has  
many
 utilities for our health and  
positive
 impact for environment. I  
agree
 with this approach.  
But
, in my opinion, all species exist for each other. How the  
animals
 need each other for living,  
people
  also
 may consume the farm  
animals
 or fishes.  
Because
 we may obtain the certain types of nutrition from  
animals
.  
But
  also
, I believe that, if we  
keep
 the balance to consumption of  
meat
, fish, vegetable, this would  
make
 our body more healthier than to become vegeterian.