Fish in Qt

#!/usr/bin/python3
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtWidgets import QApplication, QWidget
from PyQt5.QtGui import QPainter, QPixmap, QBitmap, QColor

MAX_SIZE = 250

class FishWindow(QWidget):
  def __init__(self):
    super().__init__()
    fishPixmap = self.loadFish("fish.png")

    self.setFixedSize(fishPixmap.size())

    # fishMask = fishPixmap.createMaskFromColor(QColor(0, 0, 0, 0), Qt.MaskOutColor)
    fishMask = fishPixmap.createMaskFromColor(QColor(0, 0, 0, 0), Qt.MaskInColor)
    # fishMask = fishPixmap.createHeuristicMask()
    self.setMask(fishMask)

    self.setWindowFlags(Qt.FramelessWindowHint | Qt.WindowMaximizeButtonHint)
    self.setAttribute(Qt.WA_TranslucentBackground, True)
    self.dragPosition = QPoint(0, 0)
    self.fishPixmap = fishPixmap
    self.windows = list()

  def loadFish(self, fileName):
    fishPixmap = QPixmap("fish.png")
    fishSize = fishPixmap.size()

    if fishSize.height() > fishSize.width():
      height = MAX_SIZE
      width = int(MAX_SIZE * fishSize.width() / fishSize.height())
    else:
      width = MAX_SIZE
      height = int(MAX_SIZE * fishSize.height() / fishSize.width())

    fishPixmap = fishPixmap.scaled(width, height, Qt.KeepAspectRatio)
    return fishPixmap

  def paintEvent(self, event):
    painter = QPainter(self)
    painter.drawPixmap(0, 0, self.fishPixmap)

  def mouseReleaseEvent(self, event):
    if event.button() == Qt.LeftButton:
      event.accept()
      self.newFish()

  def mousePressEvent(self, event):
    if event.button() == Qt.LeftButton:
      # self.dragPosition = event.globalPos() - self.frameGeometry().topLeft()
      self.dragPosition = self.mapFromGlobal(event.globalPos())
      event.accept()

  def mouseMoveEvent(self, event):
    if event.button() == 0:
      self.move(event.globalPos() - self.dragPosition)
      event.accept()
  def newFish(self):
    window = FishWindow()
    window.move(QPoint(500, 500))
    window.show()
    self.windows.append(window)

if __name__ == '__main__':
  app = QApplication([])
  fishWindow = FishWindow()
  fishWindow.show()
  app.exec_()