Introducing New Fish to Your Tank

This article will give you an idea of the sort of things to expect when you first introduce fish to your aquarium. We are going to assume that you have already cycled your tank and you have an established biological filter. If you don't understand the principle of "cycling an aquarium"then please visit this page. If you don't understand something then please visit our forum where somebody will help you. DO NOT introduce an Oscar to your aquarium until your tank is fully cycled.

Fish don't like being removed from water at the best of times. So when you buy a fish and transport it to your premises, it may put it under quite a lot of stress. When you introduce the fish to the aquarium for the first time, don't be surprised if it finds the nearest hiding place and stays there for a few hours. Young fish are more likely to take longer to settle into a tank so best give them plenty of time. It may be a good idea to leave the lights off for the first day. If the Oscar is responsive when you approach the tank then you could try turning the lights on. If he seems like he is a little scared of the aquarium lights then introduce them gradually. Fish will feel safer if the tank is not brightly lit.

Possible behavior when first introducing a fish to its tank

  • The fish bolts straight for a hiding place and may not come out for a while
  • The fish breathes heavily. More than likely this is due to stress levels [also read this section]
  • The fish floats to the bottom of the tank and appears to be motionless, sometimes laying on its side. This will also be down to stress
  • The fish won't eat. Once again, the fish has been put through a traumatic experience and will not want to eat straightaway
Always test your water after introducing fish to an aquarium. If your fish is particularly big, you may possibly get an ammonia spike. Normally these things don't last very long and if you've got a healthy biological filter, everything should be fine.