male of gudgeon or bitterling in bright spawning coloration show territorial aggression in a planted freshwater aquarium

acheilognathinae aggression amarus animal aqua aquarium aquatic background beautiful behaviour biotope bitterling blur blurred breeding bright captive clear coldwater coloration concept conditions controlled copy cyprinid dark decorative dwarf ecology endangered endemic europe european fauna fin fish fishkeeping free freshwater grey gudgeon ichthyology light line litter live local look low macro male natural nature ornamental planted protection research rhodeus river sensitive show space spawn spawning species tank temperate territorial topmouth underwater water widespread wild