deb4403 said:
We are definitely novice fishkeepers, but thought we had a stable tank. Believe it is a 55 gallon and had only a handful of swords in it, plus 2 plecs.
About three weeks ago, I changed the filter package (after washing it, of course). Then about 2 weeks ago, we added perhaps another 4 or 5 fish--swords I believe. Actually had 2 babies as well.
3 days ago we had a dead fish in the morning, but thought little of it. But in the past two days, all have died except the plecs.
The only things done to the tank were the addition of those few fish, changing the filter and refilling the tank with tap water (no, we didn't leave the water set or add any conditioners to it
)
We have no water quality testing equipment, so I can't tell you what the PH, etc. is.
Only signs are that the dead fish have bubbles around their bodies.
Any ideas of what may have happened and how we can get past this and restock the tank ? We really miss our friends, exspecially the babies.
Help
What did you wash the filter package in? If you washed it in tap water that has chlorine in it, which would kill off the beneficial bacteria in your tank. Beneficial bacteria are found in the filter and gravel and break down ammonia (from fish waste) into nitrite, and the nitrite into nitrate. This is called the Nitrogen Cycle. Ammonia and nitrite are both deadly toxic to fish - in fact, they're the most common cause of fish deaths.
The new filter would not have had the beneficial bacteria growing in it. Personally, I rarely change filter insets and when I do, I have the new inset soaking in the tank for a couple of weeks, to ensure a new bacterial culture gets growing in it. But most of the time I just rinse the filter innards out in used tank water.
When you say you "refilled the tank", can I take it you drained the tank? I hope you didn't, but if so, the bacteria in your gravel could well have died off. Adding water straight from the tap, without dechlorinating it, would mean that you then added chlorine to the dying bacteria, killing it dead (as the old toilet cleaner ad goes)
When beneficial bacteria die off in a tank the Nitrogen Cycle collapses. Immediately, ammonia levels start to rise and the tank becomes like a brand new tank that has not "cycled". After a few days, assuming your fish survive, the bacteria start to re-establish themselves and convert the ammonia to nitrite. Nitrite will finish off any fish that survived the ammonia. Plecos are usually the first to go - they are least able to swim to the surface to get the extra oxygen needed to fight off ammonia and nitrite.
Cleaning materials, if you used them, could also have contributed to the fish's death, through poisoning.
To salvage this situation you are going to have to work hard, but hopefully by the end of it you'll have a much better idea of why it went wrong and how to prevent problems in future.
1. Firstly, you need to get that tank to "cycle" i.e. get those beneficial bacteria growing again. This will take time, but the best thing you can do for the moment is get some filter innards and gravel from an established tank or pond filter - that will bring some bacteria back into your tank. I wouldn't waste any money on so-called "Bacteria" products.
2. You need to test the water to monitor how the cycle is going. This means an ammonia test kit and a nitrite (NO2) test kit. Only when both your ammonia and nitrite levels are zero can you relax and talk about re-stocking.
3. To keep your fish alive in the meantime, do a
daily water change of 10-15%. Don't change more than that at any one time as you might remove too many of the re-establishing bacteria.
4. Feed your fish every other day bare minimum rations. They are cold blooded animals so burn off far fewer calories than mammals and fasting will decrease the amount of ammonia waste they produce.
5. If you can get cheap, live plants like elodea, bung it in. Live plants can utilise ammonia and suck it out of the water, without producing the nasty side-effects of chemicals like Ammo-lock (I suggest you avoid chemicals as much as possible).
6. If you don't have any plecs left, add some Aquarium Salt as that will help the Swords cope with nitrite a little better (plecos can't cope with salt as it burns their skin).
Keep posting to this site and we'll help you get through this. Good luck!
