var orangeFish = $("#fish1Id");
var blueFish = $("#fish2Id");

fishRandomMovement(orangeFish);
fishRandomMovement(blueFish);

function fishRandomMovement(IdRef){
	var tempSpeedLeft = (Math.random() < 0.5 ? -1 : 1) * 1 + Math.floor(Math.random() * ($(window).width() - orangeFish.width()));
	var tempSpeedTop = (Math.random() < 0.5 ? -1 : 1) * 1 + Math.floor(Math.random() * ($(window).height() - orangeFish.height()));

	$.when(
		$(IdRef)
			.animate({left: tempSpeedLeft, top: tempSpeedTop}, randNum(3500, 7500)).promise()
	).done(function(){
		fishRandomMovement(IdRef);
	});
}

function randNum(min, max){
	return Math.floor(Math.random() * (max - min + 1) + min);
}