We talk about adding to many fish at once but not....

I know its stated that we shouldnt add to many fish at once due to the ammonia spike that could occur.

One thing ive never come across is what happens when removing a bunch of fish, or a single large fish at once.

A little back story....

I have a 10G with some Mosquito Fish & Corys, the tanks been set up for over a year and my parameters are 0-0-WC when above 40ish. A couple months back my son won a Gold Fish at a local fair that ended up in the tank. Even after adding the Gold Fish my parameters were still great. I had to do more frequent WCs to control the Nitrate but that would be expected. Shortly after adding the Gold Fish I started noticing the water was starting to get a little cloudy, over the next 2 or 3 months I tried everything I could possible think of to help get the water back to its normal. I tried feeding less, larger water changes, more bio media, more filter floss, etc. Nothing help, so I ended up moving the Gold Fish to our neighbors pond that had other Gold Fish in it. Within a week and a half the water was back to its normal crystal clear appearance. This leads me to my question.

Before adding the Gold Fish I was doing 1 WC a week to keep Nitrates below 40ish. After adding the Gold Fish I was needing to do 2 WCs a week. Since removing the Gold Fish even after almost a week my Nitrates are still low(10-20). I can only assume this is because my BB was used to handling the load of all the fish and now that ive removed the Gold Fish there isn't nearly as much to process. I imagine this is ok but wanted to ask to be sure that now that ive lessened the bio load its not all going to die, just slowly drop down to the amount needed for the current amount of fish?

Wayne

 

Excellent observations. Everything here makes sense—it stands to reason that your BB colonies would have adapted, and they will likely continue to do so. I would suspect that the decrease in bioload would result of a gradual lessening of your BB colonies back to homeostasis, this gradually resulting in increased nitrates and more frequent WCs like before.

What I find most interesting would be the rate at which this happens, or if there's any longstanding impact in terms of whether you've got a larger-than-usual biofilter now established, will a decreased bioload be sufficient to keep it alive (but "hungry") to the point that you'll get away with fewer WCs moving forward? I wouldn't think so, but it also strikes me as being possible.

 

Excellent observations. Everything here makes sense—it stands to reason that your BB colonies would have adapted, and they will likely continue to do so. I would suspect that the decrease in bioload would result of a gradual lessening of your BB colonies back to homeostasis, this gradually resulting in increased nitrates and more frequent WCs like before.

What I find most interesting would be the rate at which this happens, or if there's any longstanding impact in terms of whether you've got a larger-than-usual biofilter now established, will a decreased bioload be sufficient to keep it alive (but "hungry") to the point that you'll get away with fewer WCs moving forward? I wouldn't think so, but it also strikes me as being possible.

Thanks for your reply, you bring up some valid ideas about the BB staying alive but hungrythat I’ll have to keep track of and report back.

Today I checked my parameters and I was 0/0/25ish so my Nitrates are climbing but slowly.

I plan to check them again tomorrowto see how it is.

Wayne

 

I agree adding the goldfish definitely added to the bioload which was causing the cloudy water which was probably a bacteria bloom with the BB trying to catch up with a new pretty heavy bioload. Good informative thread.

 

Just a little update.

I noticed the water was starting to get a little cloudy again. So Thursday916th) I tested the water and the results were 0/0/20-30, even though the Nitrates werent at or above 40(which is when I normally do a WC) I did a water change anyways which helped some with the clarity, the next day it was back cloudy. Not knowing what else to do I decided to try skipping a day of feeding and not doing another WC until my Nitrates get to 50+. By Saturday(18th) the water was crystal clear again and is still clear as of Tuesday(21st). Ive also been feeding less. Last night(21st) I checked my parameters and they were 0/0/15-20 so it still appears that since removing the Gold Fish my Nitrates are still increasing much slower than they did before. I'm just confused as to why I'm still getting cloudy water after a WC. The water is now the clearest its been in months. I hope the BB is now back to normal because I would hate to fight this again after my next WC.

Thoughts?

Its hard for me to think its a algae bloom because if anything I have to much BB vs not enough.

PS I don't see this being a issue but around the same time I added the Gold Fish I ended up replacing my Fluval Pre-Filter with a eBay filter, 3 of them came to a pack. Ive found that all 3 of the ebay filters clogged much easier than the original Fluval I had so yesterday I order a new Fluval Pre-Filter.

Wayne

 

Your tank is still adjusting to the increase and then decrease in bio load. A bit like a Yo-Yo effect. Increased bio load, BB colonies grow more - cloudy water. Decrease bio load, BB colonies decrease (Die off). The decreased colonies added to the bio load as seen with increased nitrates - cloudy water. Add the impact of removing the pre filter that contained BB with new pre-filter that will develop BB colonies and you are seeing the swings in water clarity and parameters.

In short, with time, it will all settle down and your water will clear up. Just monitor and make water changes to keep the levels down.