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31 Posts
Discussion Starter · #1 ·
Hi all,

I don't understand what happened. I have a planted 9 gal Eheim tank that's been up for about 6 months. Had some tetras, 2 snails and some female bettas that got along well.

I'd change the water every other week, and no issues. Recently, I noticed a few dead female bettas and my snail shells empty. So I decided to do a heavy water change today since there was several deaths at once. nothing's changed in my water cleaning, just more water than usual.

Several hours later.. all my tetras are dead, 2 females were heavily suffering and the rest all appeared to have some sort of fungus. It seemed to happen in matter of hours (They looked fine this morning before I did the water change). I decided to cull them because I didn't want them suffering.

I tested the water, everything came out normal. I did not add anything new into the tank for months. Plants are growing nicely still.

Can someone give me some ideas on what has happened? Any suggestions on how to clean my tank and make sure it's ready for fish once again? I don't want to pull the plants out and empty it totally. continue water changes still?

2,862 Posts
What symptoms did they have before death?

Regarding the fungus, was it cotton-like fuzz balls/tufts or was the fish just slimy (excessive slime coat) or was the fishes body just white/pale in color? I am referring to when the fish were alive, not dead and rotting.
Any open flesh wounds?

Can you give any specs on your tanks' water parameters? (Ph, temperature, etc)
Injecting co2?

31 Posts
Discussion Starter · #4 ·
I am thinking the snails destroyed the tank upon their deaths. they were pretty old.

THe fish had cotton-like fungus and breathing hard. THey also had a hard time swimming.

I didn't test the ammonia before the WC.. after it was close to 0, so it might've been up there too.
Temp is at 76- I forget the pH, but it was good.

Been using seachem excel- nothing else in the water (no conditioners or anything at all). No CO2- root tabs, which was replaced about 3 weeks ago.

2,862 Posts
How big of a snail are you talking? I've seen tanks (even 5 gallon and 10 gallon tanks) with dead snails (rotting) and still never was a issue with water quality (if your tank is well established and just as they handle extra bioload during feeding, they can handle a couple dead snails. Even if the ammonia levels didn't stay untraceable, they should have cleared away within a short time and no real ill effects on the fish.

How long ago did the snails die? It would take some time for fish to develop disease in poor water quality.

Is there not much surface agitation?
What fish exactly had fungus? Where was the fungus locted on the fish? Any open sores/raw flesh wounds?

Who was deas first, bettas or snails?
I noticed you said "few" dead female bettas. How many did you have in there? Did they fight a lot? Plenty of hiding spaces?

31 Posts
Discussion Starter · #6 ·
I am honestly not sure when the snails died. I noticed the shells today when I was looking for a certain betta (and found dead). They were about half an inch big each. The bettas got along pretty well. no nipped fins, no open wounds or anything that I was aware of. They all piled with each other at nights.

I had 5 bettas in there. I noticed two bettas dead first this morning. After the water change, my tetras went belly up (had 3 neon tetras) first. Then the other 3 bettas each developed cloudy eyes and the cotton was in their gills. They had white splosh on their sides too.

I admit, I don't study my fish every day, so I can't be too certain if they were OK this morning before the change.. they were swimming around as usual and all were accounted for. After the water change, they all went into hiding and did not come out for feeding.

I feel like maybe i did too big of a water change and shocked them? I should get my tap water tested- maybe something changed there?

11,721 Posts
In a 9 gallon tank there may have been too much livestock.
2 snails
several Bettas
several Tetras

then water changes only every other week.

I think something was building up in this tank, and eventually killed the snails. It takes time for the snails' bodies to rot, and this created the ammonia that killed the fish.

At this point:
I would take everything apart and clean it all, thoroughly rinse the substrate and filter media.
If you suspect a disease killed the livestock then you could clean everything with diluted bleach: 1 part bleach:19 parts water. Or you could use straight Excel (Do this outside, and do not breath the fumes) Then rinse with water (with a double dose of dechlor if you use bleach). Air drying will also allow the bleach to evaporate.

The reassemble it:
Substrate, rock, wood, other hardscape elements.
Plant, misting as needed.
Put a plate or plastic bag over the substrate and fill with all new water (don't forget the dechlor!)
Add equipment while it is filling, and turn on the equipment when the tank is full.

Then do the fishless cycle. You will need testing supplies for this. The strips are just fine. Get strips for ammonia, nitrite, nitrate, GH, KH, pH (The ammonia is on a separate strip, all the others are on 5-way and 6-way strips).
The nitrifying bacteria population will be lower after such a thorough cleaning (especially if you use bleach).
Also, the time it takes to do the fishless cycle will allow disease organisms a chance to die, because there is no host in the tank. I would give it a month like this. Even if the fishless cycle finishes early, keep on running the tank and feeding the bacteria some ammonia for the rest of the month.

Read up about stocking the tank. A 9 gallon is not a large tank, and when something goes wrong it can go wrong really fast. Under stock!
If you like Bettas, perhaps 3 females, and no other fish.
If you like Tetras or other schooling fish, then select the smallest such as Ember Tetras, Dwarf Rasboras or similar sized fish (these are about an inch long) and get 6-8 but no other fish.

Here is the fishless cycle.

Cycle: To grow the beneficial bacteria that remove ammonia and nitrite from the aquarium.

Fish-In Cycle: To expose fish to toxins while using them as the source of ammonia to grow nitrogen cycle bacteria. Exposure to ammonia burns the gills and other soft tissue, stresses the fish and lowers their immunity. Exposure to nitrite makes the blood unable to carry oxygen. Research methemglobinemia for details.

Fishless Cycle: The safe way to grow more bacteria, faster, in an aquarium, pond or riparium.

The method I give here was developed by 2 scientists who wanted to quickly grow enough bacteria to fully stock a tank all at one time, with no plants helping, and overstock it as is common with Rift Lake Cichlid tanks.

1a) Set up the tank and all the equipment. You can plant if you want. Include the proper dose of dechlorinator with the water.
Optimum water chemistry:
GH and KH above 3 German degrees of hardness. A lot harder is just fine.
pH above 7, and into the mid 8s is just fine. (7.5-8 seems to be optimum)
Temperature in the upper 70s F (mid 20s C) is good. Higher (to 95*F or about 35*C) is OK if the water is well aerated.
A trace of other minerals may help. Usually this comes in with the water, but if you have a pinch of KH2PO4, and trace elements like CSM+B that may be helpful.
High oxygen level. Make sure the filter and power heads are running well. Plenty of water circulation.
No toxins in the tank. If you washed the tank, or any part of the system with any sort of cleanser, soap, detergent, bleach or anything else make sure it is well rinsed. Do not put your hands in the tank when you are wearing any sort of cosmetics, perfume or hand lotion. No fish medicines of any sort.
A trace of salt (sodium chloride) is OK, but not required.
This method of growing bacteria will work in a marine system, too. The species of bacteria are different.

1b) Optional: Add any source of the bacteria that you are growing to seed the tank. Cycled media from a healthy tank is good. Decor or some gravel from a cycled tank is OK. Live plants or plastic are OK. I have even heard of the right bacteria growing in the bio film found on driftwood. (So if you have been soaking some driftwood in preparation to adding it to the tank, go ahead and put it into the tank) Bottled bacteria is great, but only if it contains Nitrospira species of bacteria. Read the label and do not waste your money on anything else.
At the time this was written the right species could be found in:
Dr. Tims One and Only
Tetra Safe Start
Microbe Lift Nite Out II
...and perhaps others.
You do not have to jump start the cycle. The right species of bacteria are all around, and will find the tank pretty fast.

2) Add ammonia until the test reads 5 ppm. This ammonia is the cheapest you can find. No surfactants, no perfumes. Read the fine print. This is often found at discount stores like Dollar Tree, or hardware stores like Ace. You could also use a dead shrimp form the grocery store, or fish food. Protein breaks down to become ammonia. You do not have good control over the ammonia level, though.
Some substrates release ammonia when they are submerged for the first time. Monitor the level and do enough water changes to keep the ammonia at the levels detailed below.

3) Test daily. For the first few days not much will happen, but the bacteria that remove ammonia are getting started. Finally the ammonia starts to drop. Add a little more, once a day, to test 5 ppm.

4) Test for nitrite. A day or so after the ammonia starts to drop the nitrite will show up. When it does allow the ammonia to drop to 3 ppm.

5) Test daily. Add ammonia to 3 ppm once a day. If the nitrite or ammonia go to 5 ppm do a water change to get these lower. The ammonia removing species and the nitrite removing species (Nitrospira) do not do well when the ammonia or nitrite are over 5 ppm.

6) When the ammonia and nitrite both hit zero 24 hours after you have added the ammonia the cycle is done. You can challenge the bacteria by adding a bit more than 3 ppm ammonia, and it should be able to handle that, too, within 24 hours.

7) Now test the nitrate. Probably sky high!
Do as big a water change as needed to lower the nitrate until it is safe for fish. Certainly well under 20, and a lot lower is better. This may call for more than one water change, and up to 100% water change is not a problem. Remember the dechlor!
If you will be stocking right away (within 24 hours) no need to add more ammonia. If stocking will be delayed keep feeding the bacteria by adding ammonia to 3 ppm once a day. You will need to do another water change right before adding the fish.

Helpful hints:

A) You can run a fishless cycle in a bucket to grow bacteria on almost any filter media like bio balls, sponges, ceramic bio noodles, lava rock or Matala mats. Simply set up any sort of water circulation such as a fountain pump or air bubbler and add the media to the bucket. Follow the directions for the fishless cycle. When the cycle is done add the media to the filter. I have run a canister filter in a bucket and done the fishless cycle.

B) The nitrogen cycle bacteria will live under a wide range of conditions and bounce back from minor set backs. By following the set up suggestions in part 1a) you are setting up optimum conditions for fastest reproduction and growth.
GH and KH can be as low as 1 degree, but watch it! These bacteria may use the carbon in carbonates, and if it is all used up (KH = 0) the bacteria may die off. They use the carbon from CO2, and this is generally pretty low in water, but can be replenished from the air and from carbonates. Keep the carbonates up to keep the pH up, too.
pH as low as 6.5 is OK, but by 6.0 the bacteria are not going to be doing very well. They are still there, and will recover pretty well when conditions get better. To grow them at optimum rates, keep the pH on the alkaline side of neutral.
Temperature almost to freezing is OK, but they must not freeze, and they are not very active at all. They do survive in a pond, but they are slow to warm up and get going in the spring. This is where you might need to grow some in a bucket in a warm place and supplement the pond population. Too warm is not good, either. Tropical or room temperature tank temperatures are best. (68 to 85*F or 20 to 28*C)
Moderate oxygen can be tolerated for a while. However, to remove lots of ammonia and nitrite these bacteria must have oxygen. They turn one into the other by adding oxygen. If you must stop running the filter for an hour or so, no problem. If longer, remove the media and keep it where it will get more oxygen.
Once the bacteria are established they can tolerate some fish medicines. This is because they live in a complex film called Bio film on all the surfaces in the filter and the tank. Medicines do not enter the bio film well.
These bacteria do not need to live under water. They do just fine in a humid location. They live in healthy garden soil, as well as wet locations.

C) Planted tanks may not tolerate 3 ppm or 5 ppm ammonia. It is possible to cycle the tank at lower levels of ammonia so the plants do not get ammonia burn. Add ammonia to only 1 ppm, but test twice a day, and add ammonia as needed to keep it at 1 ppm. The plants are also part of the bio filter, and you may be able to add the fish sooner, if the plants are thriving. 1 ppm twice a day will grow almost as much bacteria as 3 ppm once a day.

3,702 Posts
I had a large ramshorn snail die and foul my water for 2 days.
No ammonia but a nitrite spike in a 55 gallon.
It recovered on it's own though, I did remove what was left of the snail.

Your tank may not have a crashed nitrogen cycle though.
Can you dose say 1ppm of NH3 and see how long it takes to recover?

Fungus is another story, do you have a pic of such fungus on your fish?

If your nitrogen cycle is indeed intact I would suggest Paraguard treatment as a precautionary measure against the fungus. That is if it was a true fungus and not just something growing on an already dead fish.

Water parameters would help.

4,221 Posts
You might check with the water company, perhaps they changed the way water is treated. More and more are going to chloramine which cannot be degassed by bubbling for 24 hours the way that chlorine can.
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