Почему методы не делают то что должны? - C#

 public class ZooManagement
    {
        public Animal[] AnimalsList;
        public int length = 0;
        public int max_size;
 
        public void DisplayMenu() {
            int choice;
            try
            {
                do
                {
                    Console.Write("Welcome to our zoo menu\n\n");
                    Console.Write("1. To add Animal\t");
                    Console.Write("2. To remove Animal\t");
                    Console.Write("3. To Display Animals ");
 
                    choice = int.Parse(Console.ReadLine());
                    switch (choice)
                    {
                        case 1:
                            //.Add();
                            break;
                        case 2:
                            //.Remove();
                            break;
                        case 3:
                            //.Display();
                            break;
                        default:
                            Console.WriteLine("You've pressed something elss");
                            break;
                    }
                    Console.Write("\n\n\t\t\tNow press any button");
                    Console.ReadLine();
                    Console.Clear();
                }
                while (choice != 3);
            }
            catch (Exception ex)
            {
                Console.WriteLine("Dont't be like that");
            }
        }

       ////////////////////////////////////////////////////
 
        public ZooManagement(int x)
        {
            this.AnimalsList = new Animal[x];
            max_size = x;

        }
 
        //public void Array(int x)
        //{
        //    this.AnimalsList = new Animal[x];
        //    max_size = x;
        //}

        public void Add(Animal x)
        {
            if (this.length > this.max_size)
            {
                Console.WriteLine("Out of bound Exception, Array full");
            }
            else
            {
                this.AnimalsList[this.length] = x;
                this.length++;
            }
        }
 
        public void Add(int h, Animal x)
        {
            if (h > this.length || h < 0)
            {
                Console.WriteLine("Out of bound Exception");
            }
            else
            {
                for (int i = (this.length); i >= h; i--) {
                    this.AnimalsList[i + 1] = this.AnimalsList[i];
                }
                this.AnimalsList[h] = x;
                this.length++;
            }
        }
 
        public void Remove(Animal x)
        {
            int FoundAt = -1;
            for (int i = 0; i < this.length; i++)
            {
                if (this.AnimalsList[i] == x)
                {
                    FoundAt = i;
                    break;
                }
            }
            if (FoundAt != -1)
            {
                for (int i = FoundAt; i < this.length; i++)
                {
                    this.AnimalsList[i] = this.AnimalsList[i + 1];
                }
                this.length--;
            }
        }
 
        public void Remove(int x)
        {
            if (x > this.length || x < 0)
            {
                Console.WriteLine("Out of bounds exception");
            }
            else
            {
                this.AnimalsList[x] = null;
                for (int i = x; i < this.length; i++)
                {
                    this.AnimalsList[i] = this.AnimalsList[i + 1];
                }
                this.length--;
            }
        }

        public Animal GetAnimal(string reign)
        {
            if ("fish".Equals(reign))
            {
                return new Fish("", 0, 0, "", "");
            }
            else if ("reptile".Equals(reign))
            {
                return new Reptile("", 0, 0, "", "");
            }
            return null;
        }
 
        public Animal Get(int x)
        {
            if (x > this.length || x < 0)
            {
                Console.WriteLine("Out of bounds Exeption");
                return null;
            }
            else
            {
                return this.AnimalsList[x];
            }
        }
        public void Set(int h, Animal x)
        {
            if (h > this.length || h < 0)
            {
                Console.WriteLine("Out of bounds Exeption");
            }
            else
            {
                this.AnimalsList[h] = x;
            }
        }
 
        public void Swap(int x, int y)
        {
            if (x >= 0 && x < length && y >= 0 && y < length)
            {
                Animal temp = AnimalsList[x];
                AnimalsList[x] = AnimalsList[y];
                AnimalsList[y] = temp;
            }
            else
            {
                Console.WriteLine("Out of bounds exception");
            }
        }
 
        public void Swap(Animal x, Animal y)
        {
            int FoundAtA = -1;
            int FoundAtB = -1;
 
            for(int i = 0; i <this.length; i++)
            {
                if(this.AnimalsList[i] == x)
                {
                    FoundAtA = i;
                    if(FoundAtA != -1 && FoundAtB != -1)
                        {
                        break;
                        } 
                }
                else if(this.AnimalsList[i] == y)
                {
                    FoundAtB = i;
                    if(FoundAtA != -1 && FoundAtB != -1)
                    {
                        break;
                    }
            }
        }
            if (FoundAtA != -1 && FoundAtB != -1)
            {
                this.Swap(FoundAtA, FoundAtB);
            }
            else
            {
                Console.WriteLine("Out of bounds Exeption");
            }
        }
 
        public void Display()
        {
            for (int i = 0; i < this.length; i++)
            {
                Console.WriteLine(this.AnimalsList[i]);
            }
        }
    }
        //public static double AnimalWeight(int weight, int size)
        //{
        //    return (weight * 703) / (size * size);
        //}
}

class Program
    {
        delegate void GetMessage();
 
        static void Main(string[] args)
        {
            ZooManagement x = new ZooManagement(10);
            Console.WriteLine("\n");
            Animal petru = new Fish("Piranha", 22, 33, "M", "round");
            Animal petra = new Reptile("Snake", 33, 44, "F", "long");
            x.Add(4, petru);
            x.Add(5, petra);
            x.Display();
            x.Swap(petru, petra);
            x.Display();
            Console.ReadKey();
            x.DisplayMenu();}}

 class Fish : Animal, IFood ,ILimbless
    {
        public string shape;
 
        public string Shape { get; set; }
 
        private string GetFishShape(string shape)
        {
            return shape;
        }
 
        public override string Behavior()
        {
            return "Passive";
        }
 
        public void  Eats()
        {
            Console.WriteLine( "Eats alges and fish");
        }
 
        public override string MakeNoise()
        {
            return "Doesnt make noises LOL";
        }

        public void Slither(string w)
        {
            Console.WriteLine("It is limbless that's why it slithers");
        }
 
        public Fish(string raceInfo, int weight, double size, string sex, string shape) : base(raceInfo, weight, size, sex)
        {
            this.raceInfo = raceInfo;
            this.weight = weight;
            this.size = size;
            this.sex = sex;
            this.shape = shape;
        }
 
}

   public abstract class Animal
    {
        public string raceInfo;
        public int weight;
        public double size;
        public string sex;
 
        public string RaceInfo { get; set; }
        public int Weight { get; set; }
        public double Size { get; set; }
        public string Sex { get; set; }
 
        public Animal(string raceInfo, int weight, double size, string sex)
        {
            this.raceInfo = raceInfo;
            this.weight = weight;
            this.size = size;
            this.sex = sex;
        }
        public abstract string Behavior();
        public abstract string MakeNoise();
     
    }
}