Advice On Koi In Aquarium

Let me start by saying that I’m not new to fishkeeping, but am rather new to aquariums. It’ll probably be better to explain the story than just ask questions.

I rebuilt a 2,000 gal pond about 2 years ago, and stocked it with koi and goldfish. It took a while to learn the ins and outs, but I did pretty well at maintaining the water and environment, and aside from a heron eating a few here and there I lost just one fish in 2 years.


Fast forward to last month, I very abruptly had to move from my house with the pond. Considering the investment in the fish and the fact that I really liked them, I decided there was no way I could leave them behind. Especially the koi.

I understand that koi really aren’t best kept in aquariums and really do best when in a pond. Considering I live in northeast Ohio, it was already too cold to build a pond on such short notice. I intend to build one in the spring.

So, when I moved, I had to figure out a solution, so I bought 2 60 gal aquarium kits to move the fish over to. Aside from the nightmare of getting them out of the pond (equally stressful for me and them, lol) I brought them to their new winter homes.

I have: 2 marineland 60 gal aquariums w/ stand, 75-ish lbs of gravel per tank, and a Penn-Plax Cascade 700 canister filter in each tank.



The koi are mostly in one tank and the goldfish mostly in another. I’m working on getting my mom or some friends to take some of the fish, but until someone does, I’m stuck with all of them.

The goldfish tank seems to have cycled properly and requires little to no maintenance. It stays clear and ammonia, nitrate and nitrite are nominal. The koi tank is where I’ve been struggling. During the first two weeks, I struggled with ammonia spikes and frequent water changes. I also had to balance that with treating some mild fin rot.

2 weeks ago, I upgraded the filtration and added a zeolite filter pack and ceramic bio rings filter pack to the canister. Coupled with a large dose of Dr Tim’s one and only, the tank seemed to finally cycle. Ammonia was present, but has been very low since I added the new filter media. Over the last few days however, the water has gotten cloudy and then pH dropped. I also noticed that ammonia dropped as well. I think I had a nitrate spike. I did a 25% water change yesterday and another 25% change today.

I also added an EcoBio-Block this morning, which I’ve read some amazing reviews for. What else can you guys recommend? I'm not a big fan of chemicals, and that's why I think I was successful with the pond. I don't want to kill the fish before the spring though, and I'm still struggling with keeping the water chemistry balanced properly.

 

HI welcome to FishLore!

Keep in mind, I don't know anything about koi. Your challenge is finding the right balance of water changes vs the amount of waste produced in that amount of water.
I'm assuming both will be fairly high. Perhaps adding extra filtration for a more than healthy bacterial bed.

I'm sure others have had to winter their pond fish inside. Let's see what thy have to stay.

 

Since this is only temporary I suggest keeping up with water changes and watching those parameters closely. With that many fish ammonia is sure to creep up fast.

 

Yes since the water will be warm inside they will require enough feeding to keep you very busy in the cleaning department. Those are some very large and nice looking fish. I know what they say about opinions; mine would be that in a tank of say 120G maybe 3 large fish due to the amount of cleaning required. I know these fish can easily take Nitrates in the 100 to 160ppm range. They will keep your tanks there even with regular water changes.

Winter tank I built:

 

Yeah, I'm definitely learning these things the hard way. Certainly not as easy as the pond, but I can deal with the water changes. I think pH dropped fast from the nitrate spike...what's most recommended for that? I don't really like chemicals like pH up/pH down. I have some Tetra Easy balance but I'm wary of products that don't say what exactly they will do.

 

you mentioned not doing maintenance on your goldfish tank. I'd change that. Goldfish are very dirty fish. Maintenance is a much needed thing. Gravel vac, filter cleaning etc. You may have gotten parameter spikes because you added so many large fish to a tank at once.

 

I meant that the goldfish tank hasn’t really needed as much maintenance. I’m doing water changes and vacuuming the gravel, as well as monitoring the parameters, but that tank hasn’t required as much to stay in balance.

Would it be better to distribute the koi and goldfish more between the two tanks?

Yes since the water will be warm inside they will require enough feeding to keep you very busy in the cleaning department. Those are some very large and nice looking fish. I know what they say about opinions; mine would be that in a tank of say 120G maybe 3 large fish due to the amount of cleaning required. I know these fish can easily take Nitrates in the 100 to 160ppm range. They will keep your tanks there even with regular water changes.

Winter tank I built:

That’s a great idea. My company has 500 gal totes, maybe I should try to get one, and cycle that for the koi instead.

 

The one I got here in Michigan had been used for transport of Honey which was comforting to know that it wasn't some type of nasty stuff I would have to go crazy trying to clean out. Here those used totes run between $120-$140. The Filter was super easy to build. Pipe, 2 slip on couplings that had one side threaded, 2 threaded plugs and 2 bulkheads You may have to grind a 1/8" off one of the nuts to fit on the inside of the extruded square in the center. I bought all my media on Amazon, it usually even comes in net bags. I prefer to pack it loose as I get more media in and I separate media types with various pads. Nitrate reducing pad, cource fiber .. etc. I used thread tape on all threads.

Oh and I use a Mag Pump 9.5 has the perfect amount of turnover

 

Figured I'd follow up. First off, unless anyone knows something bad about them that I haven't heard of, EcoBio Block is amazing. It produced crystal clear water in my tanks and I think it's helping them cycle. Was still having trouble with the pH, and I found that gh/kh weren't ideal, so I did another 25% water change. I'm using SeaChem Prime to condition because it claims to detoxify nitrite and nitrate, while it cycles.

Also used SeaChem Neutral to buffer the pH back to 7 and help with gh/kh. Fish seem to be doing alright, but the koi are still acting a little erratic/stressed. I expect it takes a while for them to chill after water conditions improve.