Adding New Fish.

Hello again!

I wanted to take some time to discuss water quality with regards to the addition of new fish.

There are a lot of resources out there regarding how to test your water for various conditions (pH, hardness, salinity, temperature, ammonia, nitrites, nitrates). What I wanted to touch on, though, is the value of understanding the impact these conditions - intended or not - can have on the fish in your tank.

Lets say you've had your tank running now for 6 weeks. Inside the aquarium you've got a close to capacity stock of fish. If you had not changed the water for a while (Lets say it's been a few weeks and your water changes prior to that have been small), you may find that the conditions in your tank are not where they should be for your fish. In fact, they might be quite a bit off for targets! You might start to ask yourself why your fish seem to be okay but the new one you added today died within hours.

Here's the answer!

As the water quality gradually decreases over time with sub-par water changes and maintenance, your current fish are slowly being acclimated to the increasingly undesirable state of things. The opposite is true of the fish you just added. While you may have placed the bag in the water, let it sit for 15 minutes to match the temperature of the bank's water to the tank's water and then gone about adding your fish... What's happened here is similar to you breathing fresh clean air one minute to suddenly finding sucking on a truck's tailpipe. It's quite a shock as you might imagine!

So if you're wondering why new fish you're adding to an established tank aren't surviving... Try a 25% water change twice a few days apart before adding another friend!