Help me transfer a tiny comet goldfish to a 20 gallon tank, please!
November 7, 2016 3:49 PM   Subscribe

My 3 year old and I have recently become fish parents to Green One, a two-inch long comet goldfish. I'd like to transfer him from the 1.5 gallon tank where he's lived for the past 3 weeks to a new 20 gallon tank without murdering him (and also prove my mother wrong in the process).

On a recent visit to her grandmother's house, my mother gifted my daughter a small comet goldfish (which the kid promptly named Green One) in a tupperware container. We went out to buy him or her a tank, and my mother talked me out of getting a 10 gallon tank because "it's a thirty eight cent goldfish!" He's been in a 1.5 gallon tank ever since.

He seemed lethargic the other day, despite a water change a few days before, and I started doing some research on the internet about goldfish. Discovered that he should be minimally in a 20 gallon tank and felt a wee bit horrified. We changed his water and he instantly perked up, and we went out to buy a 20 gallon tank to place him in instead. We now have the tank, some gravel and sponge bob decorations, a hood and filter, and 20 gallons of spring water as we use a water softener at home and I've heard that's bad for aquariums. I figured we'd let the water adjust to room temperature before we make the switch.

But I started reading about nitrogen cycling and I am feeling completely overwhelmed. He's only 2 inches long (he's grown a bit already!) and it's not even clear to me if this is something I need to worry about with a fish this size. Can a more experienced goldfish parent of metafilter give me some step-by-step advice on safely transferring him to his new home?

To make the stakes even higher: my mother laughed at me when I told her I was buying the fish this new $80 tank. We kept 2 carnival goldfish in a 5 gallon tank for about a decade when I was a child, and she's currently keeping two of Green One's former feeder fish companions in a 2 gallon bowl at her house. So if I kill the fish transferring him to a bigger tank it will be extra embarrassing, especially seeing as my tendency to research and nerdery with pets vs her more cavalier old school ways were always a sticking point growing up. Plus, I'm growing really fond of Green One, as is my kid; he already runs to the edge of the tank to beg to be fed when we pass (I have been careful not to overfeed). I'd really like to see him live a long, happy life in his new digs, and could even see getting a goldfish pond someday if we're successful.

But one step at a time! How do I get him in the new bigger tank without killing him, first?
posted by PhoBWanKenobi to Pets & Animals (9 answers total) 3 users marked this as a favorite
This comment from 2007 is what I point people to for goldfish care. A+ comment, would not kill fish again.
posted by phunniemee at 4:28 PM on November 7, 2016 [8 favorites]

Great advice in the link above. Your new tank needs to cycle before you add fish. Set up the new tank and get the filter and heater running. Change the water in the goldfish bowl, but take the dirty water and add it to the new aquarium. Leave fish in the bowl. Keep the new tank empty for a week or two before adding your goldfish. Don't hesitate to take a water sample to your local fish store and ask them to test it for safety.
posted by gnutron at 5:22 PM on November 7, 2016 [2 favorites]

Response by poster: I thought that goldfish didn't need heaters?
posted by PhoBWanKenobi at 5:26 PM on November 7, 2016

I'm a tropical fish person, not a goldfish person, but the technical aspects are pretty similar once you take out the heater element.

You might want to do some googling on the term "Fish in cycling", which is growing the beneficial bacteria in the tank while the fish is living in the tank. A lot of people will say to do fishless cycling (i.e. feeding the tank ammonia with fish food or pure ammonia), and generally I agree, but I think when you actually have the fish right now it's better to get them into the tank rather than have them in a scummy bowl for all that time it takes the tank to cycle.

Long story short, you'll want to make sure you have an ammonia and nitrite test kit (Liquid tests with dropper bottles, NOT the strips, strips are less accurate). You test the water every day, and whenever the tests detect ammonia or nitrite over .25 ppm, change half the water and test again to make sure you've gotten it down below that. If fishy ever looks distressed and the test isn't up to .25 ppm ammonia/nitrite yet, go ahead and change the water anyways, better safe than sorry. You should see ammonia spike up first (which is the fish waste), and if you start seeing nitrite that means bacteria have begun to grow in the filter and are converting the ammonia into slightly less harmful nitrite. Eventually you should see less and less ammonia and nitrite, and eventually none at all. The last and only chemical you should see if everything went well is nitrAte, but it's not harmful until extreme concentrations and you should be keeping that under control with routine weekly 25-50% water changes anyways (and the nitrAte test kit is a real pain to get working right, you save more time just doing a water change rather than fiddling with it). You can speed this process up by sticking some filter media from an established tank into your filter (do you have any friends with fish?).

Now how do you get fishy in the tank? Get everything set up, get the filter running, make sure the water has all come to room temperature. Since you're using springwater you shouldn't need to dechlorinate, but some dechlorinators have an added stress-coat so if you have that go ahead and toss it in with the dose designated on the bottle. Turn the tank lights off, keep the room lights low. Put fishy in a tupperware filled with his current bowl water and float it in the tank. Get a little spoon or measuring cup and every 5 minutes swap a little of the tupperware water with a little of the tank water. This will make sure if there's any chemical differences between the two, his body has time to acclimate. Do this until you've changed out approx the whole volume of the tupperware, then go ahead and let him loose into the tank. Keep the lights low and area quite for a day or two.

For water changes, leave fishy in the tank, buy a siphon at the petstore and a bucket and use that, lightning fast and you can vacuum up fish poops while you're at it. Changing water with a cup will take you a million years. And read up about your filter, generally they have a sponge or pellet insert that stay in the filter so the bacteria have a place to live, you don't want to clean this or else you're back at square one. Rinsing/squeezing filter media in old tank water you've siphoned out is OK.
posted by Orca at 5:53 PM on November 7, 2016 [1 favorite]

I had a forty gallon tank. It had an under gravel filter. I had all kinds of fish and crabs in there. I never changed the water, but only put in spring water that had very low mineral content. I kept some sucker fish to clean the sides. I never tested the ph, or the ammonia or anything. Everything lived. The crabs escaped and tried to make a new life in the kitchen by the cat food dish, but that was the only blip in the long life of the residents of that tank.
posted by Oyéah at 7:04 PM on November 7, 2016 [5 favorites]

My bad. Goldfish don't need the same heaters that tropical fish do.
posted by gnutron at 8:18 PM on November 7, 2016

I bought an expensive chemical testing/cycling kit when I got my free goldfish, and I haven't used it much since. If I lived near you I would loan it to you (but I don't). Post on craiglist asking for a loan or gift kit?
posted by bq at 8:21 PM on November 7, 2016

Under gravel filters are the business. Simple, reliable, easy. If you put two in a 20 gallon tank so the filter plates cover most of the bottom, and use a layer of polyester wool under the gravel, then once it's been up and running for a couple of weeks you'll find that Green One will go months before you see detectable ammonia or nitrites in the water.

Throwing in a bit of duckweed every now and then will keep fishy happily shaded and fed as well as recycling nitrogen.

Main thing with goldfish is do not overfeed them. They live on the smell of a shrimpy rag.
posted by flabdablet at 7:32 AM on November 8, 2016

If you put in his old water and any gravel etc., that will help with cycling. The idea with cycling is there are bacteria that process the fish's waste and they take time to become enough in number to handle the waste. In a tank this big, the waste should be more diluted and therefore less dangerous to the fish too.

(I think you'd be fine with a 10-gallon tank but more fish tank means you can get more fish so... They are definitely happier with more than a few gallons, though.)

For future partial water changes, there may be something you can buy that you add just a few drops of to your tap water. Cheaper than spring water for sure. Actually you may want that regardless.

To move him - they use little nets at the store, you can probably just pour him out of his current bowl assuming no rocks or anything in it. Fill current tank halfway, pour in new fishy with 1 gallon already-used-to water, fill rest of the way.
posted by Lady Li at 2:57 AM on November 9, 2016

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