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588 Posts
Discussion Starter · #1 ·
In my 30 gallon, I had 5 guppies and 5 cardinal tetras. Plus other fish but none of them have been affected, yet. I have been wanting to get more cardinals, and have a 10 gallon cycling that I am looking to move my guppies to.

I went to a LFS just to see if they had any more cories, and discovered they had gotten some cardinal tetras as well. They only had two left, so I opted to purchase them.

I do not quarantine, but I do let the bag sit in the water to get up to temp for like 30 mins and then slowly add a little water for another 30 mins, then eventually put them in the tank. Normally I do this with a net as to not get any of the water from the LFS in the tank. With these cardinals that was next to impossible so I just dumped them in.

A day later, one of my guppies died. It was one of my older ones (but only about a year) so I thought maybe it was random. I wanted to avoid a water change as to not cause any issues for the two new additions, but it was time for one so I did. One of the new cardinals died instantly. I again thought perhaps this was random.

I returned the cardinal, and they had received some more so I exchanged it. Again, did my normal routine for introducing the new fish, only this time was able to catch it with the net as to not introduce the water to my tank. 2 more guppies died the next day. They would suddenly seem to have the "shivers" and then be belly up.

I am worried now that I have done something wrong. Water params are all fine by my API test kit, even had the LFS test the water. None of my other fish seem affected (scissor tail rasboras, otos, and flying fox).

Should I report the problem to the LFS? Should I start setting up a quarantine tank? Is this all just random and perhaps my guppies are just expiring? Honestly, I have not had the best of luck with guppies from the stores I have purchased from, but I have been told before it is probably because they are over-bred.

Any thoughts or advice welcome, thanks!

588 Posts
Discussion Starter · #3 ·
You likely introduced a disease into your tank. It's expected when you don't quarantine new fish.

If they're dying fast, it might be columnaris.
I had a feeling. Never had a single problem until now.

Any suggestions?

Also, how are other users here working with a quarantine tank? I have started to look up some info.

11,721 Posts
1) Guppies are hard water fish. They thrive in water with GH and KH that are much higher than Cardinals can handle. They do just fine with a little salt, though salt is optional. The best Guppies I ever had were in my brackish water tank.
2) Cardinal Tetras can store calcium all too well, and when kept in hard water (high GH) can store so much calcium it kills them. They are soft water fish.

I keep these species in separate tanks.

Quarantine tank:
Any size, but 10 gallons is a good size for small fish and just a few at a time.
Bare bottom. This way you can be sure of doing a complete cleaning when you vacuum, for example to remove fallen parasites. I put the tank on a dark shelf, so it is sort of like the bottom of a river, and put a very light scattering of fine gravel on the bottom. IMO this sort of holds the poop so that when I vacuum it is not flying all over the tank. Gotta move the siphon VERY slowly!
Add some plant trimmings, or a rock that the fish can hide in. Not much, you need to be able to see the fish and to be able to clean the tank. But they need the security of being able to hide at least somewhat. Choose something that can be thrown away or sterilized.
Plants are also good to remove the nitrogen.
A cycled filter. This could be as simple as a sponge filter that you keep running in the main tank, or some of the filter media from the main tank's filter, added to a small HOB that is the right size for the q-tank. Or, you can keep the Q-tank cycled by feeding it ammonia like doing the fishless cycle or fish food equal to more than the amount you would normally feed. I have done this in between fish purchases. If you put the media back into the main tank I sterilize it first, just in case there is something that might infect the main tank. This also kills the beneficial bacteria, but they can regrow.
Heater, light.

You want the water in the Q-tank to match the water the fish are acclimated to in the store. You will need to do some testing to set this up. I know the water parameters of the stores where I usually buy fish, and can set up the Q-tank ahead of time.
Here is how:
Start with water that you know is softer than the water in the store. You can set up the Q-tank ahead of time.
Test the water in the bag when you get the fish. (dip stick test is fast, and close enough, usually)
Raise the GH and KH in the tank to match the water in the bag.
Add whatever else you need to make the TDS match. This might be salt (many stores salt their fresh water). Plant fertilizers can raise the TDS, too, but not by much.
Good idea not to add the store water to the tank. Here is how:
Hold a net over a bucket.
Pour the water and fish out of the bag, through the net.
The fish will get caught by the net.
Hint: Have some good water in the bucket already. If the net is long enough it will hang down into the bucket and will be partially under water. When the fish land in the net they will be under water, less stress. Then you can lift them quickly to the tank.

While the fish are in quarantine:
I treat ALL bottom fish for internal parasites. Probably a good idea to treat all fish for internal parasites. Prazi pro is a good product, and I have also used home made food with medication that is sold as dog and cat wormer.

Have a UV sterilizer handy. If the store the fish came from had ANY Ich in ANY tank, then run the UV for 48 hours. Just in case. Then turn it off and watch like a hawk. Be ready to turn it on again at the first sign of Ich. Do not use any other medication with a UV sterilizer, it can degrade some meds.

If the store water and your main tank water are different (harder, softer, different TDS) then gradually alter the parameters in the Q-tank so they match. For example, one store near me has much harder water, and they salt it. (The fish could go right into my brackish water tank!) so each water change on the Q-tank adds less and less minerals and salt so the water is slowly made softer. This should take time. Fish cannot acclimate to significantly different water in just a few hours. Their metabolism needs to alter to adjust to different mineral levels in the water. Let it take a month or more. By the time the fish are ready to move into the main tank they are acclimated to the water parameters and I am sure they have no diseases.

If the fish die in the Q-tank:
Sterilize everything.
You could run most of these through the dishwasher, or boil them, or dip them in bleach. A good wipe down with bleach (50/50) can kill a lot of things.
Throw away the plants. No way to sterilize them without killing them.
Air dry will kill a lot of things. So bleach, then air dry until the chlorine has evaporated.
UV from the sun can kill a lot of things.

If you suspect Mycobacteriosis:
Wipe down with bleach (50/50 is fine)
Wipe down with rubbing alcohol, at least 70%.
This is because MB cannot be killed by bleach, but bleach dissolves the film it may live in. MB is killed by strong isopropyl alcohol, sold in the US as rubbing alcohol.
Throw away anything that cannot tolerant this treatment.
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