diff --git a/src/Entity.h b/src/Entity.h
index 3e7ffd6..de9f3b4 100644
--- a/src/Entity.h
+++ b/src/Entity.h
@@ -5,15 +5,20 @@
 #include <unordered_map>
 #include <vector>
 
+struct AssetPair {
+  std::vector<std::string> image;
+  std::vector<std::string> mask;
+};
+
 class Entity {
 protected:
   float x;
   float y;
 
 public:
-  Entity() : x(0), y(0) {}
-  virtual ~Entity() {}
+  Entity() : x(0.0f), y(0.0f) {}
+  virtual ~Entity() = default;
 
-  inline float getX() const { return x; }
-  inline float getY() const { return y; }
+  float getX() const noexcept { return x; }
+  float getY() const noexcept { return y; }
 };
diff --git a/src/Fish.cpp b/src/Fish.cpp
index 46142dc..8a77d65 100644
--- a/src/Fish.cpp
+++ b/src/Fish.cpp
@@ -4,81 +4,98 @@
 #include "assets/FishAssets.h"
 #include <ncurses.h>
 
-Fish::Fish() : Fish(getRandomFishAsset()) {}
+std::unordered_map<char, char> Fish::color_map;
 
-Fish::Fish(const FishAssetRef &pair)
-    : Entity(),
-      speed((pair.index % 2 == 0) ? Random::floatInRange(0.25, 2.25)
-                                  : -Random::floatInRange(0.25, 2.25)),
-      image(pair.asset.image), mask(pair.asset.mask) {
-  y = Random::intInRange(image.size() + 6,
-                         Aquarium::getInstance().getHeight() - image.size());
+Fish::Fish() : Fish(getRandomAssetIndex()) {}
 
-  x = (speed < 0) ? Aquarium::getInstance().getWidth() : -20;
+Fish::Fish(int asset_index)
+    : Entity(), image(fishAssetPairs[asset_index].image),
+      mask(fishAssetPairs[asset_index].mask),
+      speed(Random::floatInRange(0.25f, 2.25f)),
+      moving_right(asset_index % 2 == 0) {
+  const auto &aquarium = Aquarium::getInstance();
+
+  y = Random::intInRange(static_cast<int>(image.size()) + 6,
+                         aquarium.getHeight() - static_cast<int>(image.size()));
+
+  x = moving_right ? -20.0f : static_cast<float>(aquarium.getWidth());
 
   randomizeMask();
 }
 
 void Fish::randomizeMask() {
-  std::unordered_map<char, char> colorMap{{'4', 'W'}};
+  // Clear and rebuild color map
+  color_map.clear();
+  color_map['4'] = 'W'; // White is always '4'
 
+  // Assign random colors to digits 1-3, 5-9
   for (char digit = '1'; digit <= '9'; ++digit) {
     if (digit != '4') {
-      colorMap[digit] =
-          availableColors[Random::intInRange(0, availableColors.size() - 1)];
+      color_map[digit] = AVAILABLE_COLORS[Random::intInRange(
+          0, static_cast<int>(AVAILABLE_COLORS.size()) - 1)];
     }
   }
 
+  // Apply color mapping to mask
   for (auto &line : mask) {
     for (char &ch : line) {
-      if (auto it = colorMap.find(ch); it != colorMap.end()) {
+      if (auto it = color_map.find(ch); it != color_map.end()) {
         ch = it->second;
       }
     }
   }
 }
 
-Fish::FishAssetRef Fish::getRandomFishAsset() {
-  int index =
-      Random::intInRange(0, static_cast<int>(fishAssetPairs.size()) - 1);
-  return FishAssetRef{index, fishAssetPairs[index]};
+int Fish::getRandomAssetIndex() {
+  return Random::intInRange(0, static_cast<int>(fishAssetPairs.size()) - 1);
 }
 
-void Fish::update() { x += speed; }
+void Fish::update() noexcept { x += moving_right ? speed : -speed; }
 
-void Fish::draw(int layer) {
-  Aquarium &aq = Aquarium::getInstance();
+void Fish::draw(int layer) const {
+  auto &aquarium = Aquarium::getInstance();
+
+  // Pre-allocate strings to avoid repeated allocations
+  std::string current_segment;
+  std::string current_colors;
+  current_segment.reserve(32); // Reserve reasonable capacity
+  current_colors.reserve(32);
+
+  const int base_x = static_cast<int>(x);
+  const int base_y = static_cast<int>(y);
 
   for (size_t i = 0; i < image.size(); ++i) {
     const std::string &row = image[i];
-    const std::string &maskRow = (i < mask.size()) ? mask[i] : "";
+    const std::string &mask_row = (i < mask.size()) ? mask[i] : "";
 
-    int baseY = y + static_cast<int>(i);
-    int cursorX = static_cast<int>(x);
-    std::string currentSegment;
-    std::string currentColors;
+    int cursor_x = base_x;
+    current_segment.clear();
+    current_colors.clear();
 
     for (size_t j = 0; j < row.size(); ++j) {
-      char ch = row[j];
+      const char ch = row[j];
 
       if (ch == '?') {
-        if (!currentSegment.empty()) {
-          aq.drawToBackBuffer(baseY, cursorX, layer, currentSegment,
-                              currentColors);
-          cursorX += currentSegment.size();
-          currentSegment.clear();
-          currentColors.clear();
+        // Flush current segment if not empty
+        if (!current_segment.empty()) {
+          aquarium.drawToBackBuffer(base_y + static_cast<int>(i), cursor_x,
+                                    layer, current_segment, current_colors);
+          cursor_x += static_cast<int>(current_segment.size());
+          current_segment.clear();
+          current_colors.clear();
         }
-        cursorX += 1;
+        ++cursor_x; // Skip transparent character
         continue;
       }
 
-      currentSegment.push_back(ch);
-      currentColors.push_back((j < maskRow.size()) ? maskRow[j] : 'k');
+      current_segment.push_back(ch);
+      current_colors.push_back((j < mask_row.size()) ? mask_row[j] : 'k');
     }
 
-    if (!currentSegment.empty()) {
-      aq.drawToBackBuffer(baseY, cursorX, layer, currentSegment, currentColors);
+    // Flush remaining segment
+    if (!current_segment.empty()) {
+      aquarium.drawToBackBuffer(base_y + static_cast<int>(i), cursor_x, layer,
+                                current_segment, current_colors);
     }
   }
 }
diff --git a/src/Fish.h b/src/Fish.h
index 6e29207..c15c176 100644
--- a/src/Fish.h
+++ b/src/Fish.h
@@ -5,28 +5,23 @@
 
 class Fish : public Entity {
 private:
-  struct FishAssetRef {
-    int index;
-    FishAsset &asset;
-  };
-
-  Fish(const FishAssetRef &ref);
-  static bool initialized;
-
-  const std::vector<std::string> &image;
-  std::vector<std::string> &mask;
-
-  static constexpr std::array<char, 12> availableColors = {
+  static constexpr std::array<char, 12> AVAILABLE_COLORS = {
       'c', 'C', 'r', 'R', 'y', 'Y', 'b', 'B', 'g', 'G', 'm', 'M'};
 
+  const std::vector<std::string> &image;
+  std::vector<std::string> mask; // Copy needed for color randomization
   const float speed;
-  static FishAssetRef getRandomFishAsset();
+  const bool moving_right;
 
-  static void initializeFishAssets();
+  // Static color map to avoid recreation
+  static std::unordered_map<char, char> color_map;
+
+  explicit Fish(int asset_index);
+  static int getRandomAssetIndex();
   void randomizeMask();
 
 public:
   Fish();
-  void update();
-  void draw(int layer);
+  void update() noexcept;
+  void draw(int layer) const;
 };
diff --git a/src/assets/FishAssets.h b/src/assets/FishAssets.h
index d94e32f..9bd29ec 100644
--- a/src/assets/FishAssets.h
+++ b/src/assets/FishAssets.h
@@ -1,14 +1,9 @@
 #pragma once
 
-#include <string>
+#include "../Entity.h"
 #include <vector>
 
-struct FishAsset {
-  std::vector<std::string> image;
-  std::vector<std::string> mask;
-};
-
-inline std::vector<FishAsset> fishAssetPairs = {
+inline std::vector<AssetPair> fishAssetPairs = {
   {
       {
        R"(???\)",