Why Do Newly Introduced Fish Die

[CEB]

I had a thread a while ago asking the same question. The conclusion seemed to be that I had old tank syndrome. I thought I had solved this by doing large regular water changes.

A few weeks ago, I inherited two fish from my Mum, a Plec and another I have yet to identify. The Plec looked like he then develped an internal bacterial infection which I treated and he looked better. Yesterday he died suddenly.

What annoys me is that I keep my tank quite clean. My Mum's tank was hardly ever cleaned, and when it was it was a 50% job with untreated water added. Dead fish were not removed from the tank, and were 'recycled' let's say.

Can a tank be too sterile? How comes this fish survived months/years of neglect in a small tank, but when introduced to mine, it lasts less than a month?

I have the same problem with new fish bought from different LFSs, and also with plants I buy (but I think that's lack of CO2, now being rectified). Algea seems to do well though .

ph and other conditions seem to be perfect. I'm stumped.

Please advise if you can.

 

[Tolak]

What acclimation procedure do you follow, and do you have a quar tank for the new fish?

 

[CEB]

Acclimatisation: Float the fish in the bag for at least 10 mins, then very gradually introduce tank water to the bag over maybe 30 mins, before letting the fish out.

Quarantine: no, I don't have a quatantine tank.

 

[Tokis-Phoenix]

What sorts of fish are you buying which are dying on you? Some types of fish tend to be more difficult to settle into a new tank than others. Was the pleco thin-looking when you got him?

 

[CEB]

The Plec looked fine and health. Got dark and listless when affected by the internal bacteria, then perked up a bit before dying.

The fish I have bought have included Cardinal Tertras, Red Eye Tetras, Sucking Loach, Pepper Corydoras. From 3 different LFHs.

Current fish are 2 Cardinals, 2 Red Eyes, two other tetra (can't remember names, they're quite old), and the other one I got from Mum. All in a 250-275L tank.

 

[Tolak]

Get a quar tank, and try drip acclimating. A quar tank is not only for the benefit of the fish in your main tank, it is also for the benefit of new fish. The fish you currently have are probably settled in, with a low stress level. Stess lowers a fish's immune response. There is probably something, bacterial or otherwise, in your main tank that your current fish are living perfectly fine with, due to a healthy immune system. The new fish, being stressed from shipping and perhaps differing water parameters, have a comprimised immune system that isn't up to fighting off any bacteria they are not used to.

A quar tank doesn't have to be a glass aquarium, many folks get by with a Rubbermaid type of tub for smaller fish. It doesn't need to be a thing of beauty, a filter, heater, and some sort of top is really all that is needed, and a spartan environment is easier to keep clean and observe the new fish in.

 

[Miss Wiggle]

Get a quar tank, and try drip acclimating. A quar tank is not only for the benefit of the fish in your main tank, it is also for the benefit of new fish. The fish you currently have are probably settled in, with a low stress level. Stess lowers a fish's immune response. There is probably something, bacterial or otherwise, in your main tank that your current fish are living perfectly fine with, due to a healthy immune system. The new fish, being stressed from shipping and perhaps differing water parameters, have a comprimised immune system that isn't up to fighting off any bacteria they are not used to.

makes sense to me, do you think treating the main tank with a bacterial med could help, just to get rid of whatever is there now?

 

[CEB]

Thanks for the advice. Actually, I do have a small tank (12 inch / 30cm) but don't have any kit for it so it's not in use.

Asuming I've got a tank, how would I use it? Would I use water from the main tank (in which case, what's the point), or set it up with fresh water and cycle it before adding the new fish, then dripping in main-tank water over a long time. In this case, I'll be putting the fish into new conditions in the quarantine tank instead of new conditions in the main tank.

I'm not trying to disagree, just to understand.

Miss Wiggle, good idea. Before adding fish next time, I'll treat for existing bacterial infection.

I do occassionally use Interpet General Tonic when doing a water change. It's supposed to reduce levels of background bacteria. Usually, when I introduce new fish I dose with this as a precaution anyway.

 

[Tolak]

Get a quar tank, and try drip acclimating. A quar tank is not only for the benefit of the fish in your main tank, it is also for the benefit of new fish. The fish you currently have are probably settled in, with a low stress level. Stess lowers a fish's immune response. There is probably something, bacterial or otherwise, in your main tank that your current fish are living perfectly fine with, due to a healthy immune system. The new fish, being stressed from shipping and perhaps differing water parameters, have a comprimised immune system that isn't up to fighting off any bacteria they are not used to.

makes sense to me, do you think treating the main tank with a bacterial med could help, just to get rid of whatever is there now?

Well, you aren't certain if it is in fact a bacterial problem at this point, or a difference in water parameters. If you understand antibiotics or other meds most all do not completely eliminate bacteria, just knock it back to a lower level, allowing a fish's immune system to do a better job fighting off the remainder. Most bacteria that affect fish adversly are waterborne, that's the reason water changes are the best preventave medication in aquatics.

I start quar tanks with 100% fresh water, in a tank cleaned with a solution of 1 part bleach to 20 parts water. All equipment for that tank is cleaned that way, and all equipment is either kept seperate and specific to that tank, or cleaned with the same solution before using.

For filtration I use a spare filter running on a tank. It's wise to keep a spare filter running, you can pull it, give the media a quick rinse in fresh dechlored water, and use it on the quar tank. Due to biological exclusion there will be very little, if any, harmful bacteria contained in the cycled filter media. You could do the same thing with a little media from the cycled tank, provided it is compatable size-wise & such with the quar tank filter.

Over time, if you are keeping the same water change schedule with all your tanks they will have nearly the same water parameters, provided you don't have any driftwood, which tends to lower the pH, or lime based substrate or decorations such as rocks, which tend to raise the pH. As long as there is not a large temperature difference you can move fish from tank to tank without any problems.

Another thing I do with quar tanks & fish is allow a bit of cross contamination after a time, anywhere from 2 to 6 weeks into the quar period, depending on the fish. This allows any problems to be observed, and dealt with before any fish go into a main tank.