Awesome about the medigold- that is great, if you're dealing with bacterial septicemia... it is SUPER messy, though. The texture is almost like hamster pellets, and it does not hold together at all when pre-soaked for the fish to eat it- it crumbles, and fogs the tank. Just giving you the heads up. When I had to use it for a couple of "rescue fish" I am now caring for, I soaked a cup of it in a cup of water until it fell apart- then wizzed it through my magic bullet really quick- and then made it into a gel food, so it would hold together in the water, by heating 1/2 cup water in the microwave for 2 minutes, and then adding 4 packets of plain gelatin to that to dissolve- then mixing it all (the food slurry, and the 1/2 cup dissolved gelatin) together really well. Pour it in a plastic, lidded container, and let it sit in the fridge over night. Cut it into cubes that are about the size if 1 day's worth of feeding, leave one out to feed- freeze the rest. You can thaw a cube in the fridge over night to feed the next day for the duration of the treatment. Re-make as necessary. Treat for NO LESS than 14 days, I would actually suggest 20. The fish LOVE the medigold, so, you shouldn't have a problem with getting them to eat it, aside from getting used to the gel texture- which doesn't take long for goldies. (they may spit it out a couple of times before chowing on it.) Keep the unused medicated food pellets in the freezer, to prolong the shelf life after opening. I think if you get the ammonia situation cleared up, these problems are going to go away. BIG high five for taking in the little fish that were in need of a better home. That is definitely very sweet of you! I love those kinds of stories. You are awesome.
I agree that you need to up your filtration. Honestly, with 5 commons/comets in a 55 gallon tank- I would go for filtration that is rated for 4Xs filtration on your tank volume (so, filtration for 200+ gallons)... I know it sounds crazy, but, goldfish are messy, and they do MUCH better with over filtered water- both to deal with their mess, as well as more places for the bacteria to grow. I actually suggest one of these: http://www.ebay.com/itm/Aquarium-Ca...550?pt=LH_DefaultDomain_0&hash=item3a76d9350e I am using one on my fancy goldfish tank, and I LOVE IT!!! I am getting a second one to run on the tank as soon as I upgrade in December, too. This filter rocks my socks off. It is $100- but that is super cheap for a 4 stage canister, and you will need it when you upgrade tanks, anyways. It will have your water CRYSTAL clear. Maintenance on it isn't a bear, and it does have the built in UV sterilizer, as well. Fill 2 or 3 of the trays with ceramic rings or bioballs, and run 1 or 2 with floss- you should be good to go! You wouldn't need inserts- just bioballs, and/or bio rings (which rarely ever need to be replaced) and filter floss. Honestly, I just use quilt batting and poly fill in mine- I buy it at Walmart, and it is like $4 for a big bag of batting and $2 or 3 for a big bag of the poly fill- and will be enough to last you for months. SUPER cheap. You'd just need specific inserts for the HOB you have, which are a lot more expensive, and would add up to the difference in price between a 2nd HOB filter and the canister in a few mos. It wouldn't hurt to seed it with some Tetra Safe Start, either, when setting it up, just to give the tank a little biofilter boost. If you up the filtration, with the size fish you are describing, you do have some time before you should upgrade tanks for them. You could probably even stretch it close to a year, depending on how fast the little guys are growing, with this much filtration, and 2 50% water changes a week. Check Craigslist when you're ready to upgrade tanks- sometimes you can find a great deal on a used set-up. Until you can upgrade the filter, you might want to consider 25% water changes every other day to keep that ammonia down, if you're able to. I know, its a lot of work- do the best you can, though.
Oh, the test kit- the most commonly suggested one is the API fresh water master test kit. It seems to be the gold standard in testing. Amazon frequently runs sales on them for around $16, which is half off most LFS prices... and if you add $10 worth of more stuff to your purchase- you get the free shipping. http://www.amazon.com/API-FRESHWATE...r=8-1&keywords=api+freshwater+master+test+kit Today, they're at $20- which still isn't a bad price. With 1 tank, this thing will last you FOREVER!
BEST OF LUCK to you and little miss Penny & her other fishy friends, and have a great time on your vacation. Please let us know how things are going when you get back.
OH, and I suggest dosing with prime to block any ammonia build up while you're gone right before you leave, too!
I agree that you need to up your filtration. Honestly, with 5 commons/comets in a 55 gallon tank- I would go for filtration that is rated for 4Xs filtration on your tank volume (so, filtration for 200+ gallons)... I know it sounds crazy, but, goldfish are messy, and they do MUCH better with over filtered water- both to deal with their mess, as well as more places for the bacteria to grow. I actually suggest one of these: http://www.ebay.com/itm/Aquarium-Ca...550?pt=LH_DefaultDomain_0&hash=item3a76d9350e I am using one on my fancy goldfish tank, and I LOVE IT!!! I am getting a second one to run on the tank as soon as I upgrade in December, too. This filter rocks my socks off. It is $100- but that is super cheap for a 4 stage canister, and you will need it when you upgrade tanks, anyways. It will have your water CRYSTAL clear. Maintenance on it isn't a bear, and it does have the built in UV sterilizer, as well. Fill 2 or 3 of the trays with ceramic rings or bioballs, and run 1 or 2 with floss- you should be good to go! You wouldn't need inserts- just bioballs, and/or bio rings (which rarely ever need to be replaced) and filter floss. Honestly, I just use quilt batting and poly fill in mine- I buy it at Walmart, and it is like $4 for a big bag of batting and $2 or 3 for a big bag of the poly fill- and will be enough to last you for months. SUPER cheap. You'd just need specific inserts for the HOB you have, which are a lot more expensive, and would add up to the difference in price between a 2nd HOB filter and the canister in a few mos. It wouldn't hurt to seed it with some Tetra Safe Start, either, when setting it up, just to give the tank a little biofilter boost. If you up the filtration, with the size fish you are describing, you do have some time before you should upgrade tanks for them. You could probably even stretch it close to a year, depending on how fast the little guys are growing, with this much filtration, and 2 50% water changes a week. Check Craigslist when you're ready to upgrade tanks- sometimes you can find a great deal on a used set-up. Until you can upgrade the filter, you might want to consider 25% water changes every other day to keep that ammonia down, if you're able to. I know, its a lot of work- do the best you can, though.
Oh, the test kit- the most commonly suggested one is the API fresh water master test kit. It seems to be the gold standard in testing. Amazon frequently runs sales on them for around $16, which is half off most LFS prices... and if you add $10 worth of more stuff to your purchase- you get the free shipping. http://www.amazon.com/API-FRESHWATE...r=8-1&keywords=api+freshwater+master+test+kit Today, they're at $20- which still isn't a bad price. With 1 tank, this thing will last you FOREVER!
BEST OF LUCK to you and little miss Penny & her other fishy friends, and have a great time on your vacation. Please let us know how things are going when you get back.

OH, and I suggest dosing with prime to block any ammonia build up while you're gone right before you leave, too!

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