===================================================================
--- original.js
+++ change.js
@@ -593,11 +593,14 @@
 		var foodSources = fish.getNearbyObjects().filter(function (obj) {
 			return obj instanceof Food;
 		});
 		if (foodSources.length > 0) {
-			var closestFood = foodSources.reduce(function (closest, food) {
-				return fish.distanceTo(food) < fish.distanceTo(closest) ? food : closest;
-			}, foodSources[0]);
+			var closestFood = foodSources[0];
+			for (var i = 1; i < foodSources.length; i++) {
+				if (fish.distanceTo(foodSources[i]) < fish.distanceTo(closestFood)) {
+					closestFood = foodSources[i];
+				}
+			}
 			fish.targetRotation = Math.atan2(closestFood.y - fish.y, closestFood.x - fish.x);
 		}
 	};
 	return self;
@@ -645,8 +648,9 @@
 		} else if (self.isResting && LK.ticks - self.lastRestTime > self.restInterval) {
 			self.isResting = false;
 		}
 	};
+	return self;
 });
 var ReproductionBehavior = Container.expand(function () {
 	var self = Container.call(this);
 	self.isMating = false;
@@ -655,15 +659,18 @@
 	self.isLayingEggs = false;
 	self.lastEggTime = LK.ticks;
 	self.eggInterval = Math.random() * 3000 + 2000;
 	self.mate = function (fish, partner) {
-		if (self.isMating && LK.ticks - self.lastMateTime > self.mateInterval) {
+		if (!self.isMating && LK.ticks - self.lastMateTime > self.mateInterval) {
+			self.isMating = true;
+			partner.isMating = true;
+			self.lastMateTime = LK.ticks;
+			partner.lastMateTime = LK.ticks;
 			var egg = new Egg();
 			egg.x = (fish.x + partner.x) / 2;
 			egg.y = (fish.y + partner.y) / 2;
 			LK.stageContainer.addChild(egg);
-			self.lastMateTime = LK.ticks;
-			partner.lastMateTime = LK.ticks;
+		} else if (self.isMating && LK.ticks - self.lastMateTime > self.mateInterval) {
 			self.isMating = false;
 			partner.isMating = false;
 		}
 	};
@@ -674,10 +681,13 @@
 			var egg = new Egg();
 			egg.x = fish.x;
 			egg.y = fish.y;
 			LK.stageContainer.addChild(egg);
+		} else if (self.isLayingEggs && LK.ticks - self.lastEggTime > self.eggInterval) {
+			self.isLayingEggs = false;
 		}
 	};
+	return self;
 });
 var FeedingBehavior = Container.expand(function () {
 	var self = Container.call(this);
 	self.hunger = 100;
@@ -713,8 +723,9 @@
 			}
 		});
 		return closestFood;
 	};
+	return self;
 });
 var PlayfulBehavior = Container.expand(function () {
 	var self = Container.call(this);
 	PlayfulBehavior.prototype.playWithObject = function (fish, target) {
@@ -748,55 +759,53 @@
 var SchoolingBehavior = Container.expand(function () {
 	var self = Container.call(this);
 	self.schoolWith = function (fish, similarFish) {
 		if (similarFish.length > 1) {
-			var schoolCenterX = 0;
-			var schoolCenterY = 0;
-			similarFish.forEach(function (fish) {
-				schoolCenterX += fish.x;
-				schoolCenterY += fish.y;
-			});
-			schoolCenterX /= similarFish.length;
-			schoolCenterY /= similarFish.length;
+			var schoolCenterX = similarFish.reduce((sum, fish) => sum + fish.x, 0) / similarFish.length;
+			var schoolCenterY = similarFish.reduce((sum, fish) => sum + fish.y, 0) / similarFish.length;
 			fish.targetRotation = Math.atan2(schoolCenterY - fish.y, schoolCenterX - fish.x);
 			fish.directionChangeTime = LK.ticks;
 			fish.directionChangeInterval = 30;
 		}
 	};
+	return self;
 });
 var EvasionBehavior = Container.expand(function () {
 	var self = Container.call(this);
 	self.evadePredators = function (fish, predators) {
-		var evadeAngle = 0;
-		predators.forEach(function (predator) {
-			var angleToPredator = Math.atan2(predator.y - fish.y, predator.x - fish.x);
-			evadeAngle += angleToPredator + Math.PI;
-		});
-		evadeAngle /= predators.length;
-		fish.targetRotation = evadeAngle + (Math.random() * Math.PI - Math.PI / 2);
-		fish.directionChangeTime = LK.ticks;
-		fish.directionChangeInterval = 10;
+		if (predators.length > 0) {
+			var evadeAngle = predators.reduce(function (sum, predator) {
+				var angleToPredator = Math.atan2(predator.y - fish.y, predator.x - fish.x);
+				return sum + angleToPredator + Math.PI;
+			}, 0) / predators.length;
+			fish.targetRotation = evadeAngle + (Math.random() * Math.PI - Math.PI / 2);
+			fish.directionChangeTime = LK.ticks;
+			fish.directionChangeInterval = 10;
+		}
 	};
+	return self;
 });
 var LeadershipBehavior = Container.expand(function () {
 	var self = Container.call(this);
 	self.followLeader = function (fish, leaderFish) {
 		var followDistance = 50;
-		var dx = leaderFish.x - fish.x;
-		var dy = leaderFish.y - fish.y;
-		var distance = Math.sqrt(dx * dx + dy * dy);
+		var distance = fish.distanceTo(leaderFish);
 		if (distance > followDistance) {
-			fish.targetRotation = Math.atan2(dy, dx);
+			fish.targetRotation = Math.atan2(leaderFish.y - fish.y, leaderFish.x - fish.x);
 			fish.directionChangeTime = LK.ticks;
 			fish.directionChangeInterval = 10;
 		}
 	};
+	return self;
 });
 var MortalityBehavior = Container.expand(function () {
 	var self = Container.call(this);
 	self.die = function (fish) {
-		fish.destroy();
+		if (fish.health <= 0) {
+			fish.destroy();
+		}
 	};
+	return self;
 });
 var Surgeonfish = Fish.expand(function () {
 	var self = Fish.call(this) || this;
 	Surgeonfish.prototype.findNearestCleaner = function () {