Freshwater Tank Sudden Issue

[powerdyne6]

Hey

I have a 20 gallon freshwater setup that has recently had some sort of issue.

Tank is roughly a year old.. a no fish cycle was done at the beginning which went well and was completed in about 6 to 7 weeks.

Added 6 Penguin Tetras and a Tiger Loach

Everything has been great for the past year but last night I came home from work and one of the Tetras had died. So I was okay maybe the Loach spooked it and swam into the side of the tank or something like that. About an hour or 2 later 4 of the Tetras died (so I knew it wasn’t the Loach).

The Loach and 1 Penguin Tetra were still alive. Woke up this morning (both fish ate alive and seem fine)

Tested the water with the freshwater kit from API

PH: 6.8 to 7
Ammonia: 0ppm
Nitrite: .5 to 1ppm
Nitrate: maybe somewhere between 0 and 5ppm (most likely 0ppm)

I moved about a month ago (very short move about 3 or 4 mins up the street. Don’t think it is because of this.

My tap water has some ammonia in it but it is virtually 0ppm

For the past year I have been really good at water changes. Usually every 2 weeks (should I be doing more?) and about 50% of the water.

Any help would be great

Thanks

 

[Byron]

This would seem to be more likely a water issue rather than disease. Did you use a conditioner for the water change, and which one? Have any other additives been added to the tank water?

At previous water changes, have you vacuumed into the substrate? And kept the filter clean? The appearance of nitrite is probably the issue, as nitrite is very toxic to fish; their blood cannot carry oxygen and they die fairly rapidly, especially if the nitrite is actually as high as 1 ppm.

Do you have live plants? If yes, a photo of the entire tank will allow us to determine the extent.

Water changes should be more often, once a week should normally suffice, and change 50% or more assuming the parameters (being GH, pH and temperature) are basically the same in tap and tank water.

When you moved, did you keep the filter media wet? A month seems long before this reacted, but it may be a factor. I'm thinking the biological filtration may have been impacted, with a new cycle.

 

[powerdyne6]

This would seem to be more likely a water issue rather than disease. Did you use a conditioner for the water change, and which one? Have any other additives been added to the tank water?

I have used the API water conditioner with every change since fish were added.

At previous water changes, have you vacuumed into the substrate? And kept the filter clean? The appearance of nitrite is probably the issue, as nitrite is very toxic to fish; their blood cannot carry oxygen and they die fairly rapidly, especially if the nitrite is actually as high as 1 ppm.

I do vacuum the substrate at every water change. I have one of those all in one Fluval tanks. I have changed the biomax and carbon packs at different times throughout the year (not at the same time). I have never changed the sponge yet.

Do you have live plants? If yes, a photo of the entire tank will allow us to determine the extent.

I have a couple plants but they are not planted they are attached to a decoration.

Water changes should be more often, once a week should normally suffice, and change 50% or more assuming the parameters (being GH, pH and temperature) are basically the same in tap and tank water.

I will start doing changes once a week.

When you moved, did you keep the filter media wet? A month seems long before this reacted, but it may be a factor. I'm thinking the biological filtration may have been impacted, with a new cycle.

Filter and media was placed in a couple gallon bucket with some tank water so it stayed wet when I moved. And I did set the tank back up pretty much right away after we got to the new place.

 

[Byron]

From the above post (#3) I do not see anything that would be behind this. The nitrite at 1ppm is the issue. Have you tested the tap water for nitrite? I know you said it has ammonia, but what about nitrite? And nitrate while you're at it?

 

[powerdyne6]

From the above post (#3) I do not see anything that would be behind this. The nitrite at 1ppm is the issue. Have you tested the tap water for nitrite? I know you said it has ammonia, but what about nitrite? And nitrate while you're at it?

Just checked my tap water.. no nitrite or nitrate present.

I also just did a 50% water change

 

[Fishmanic]

What was your stocking before adding the 7 new fish? You may have disrupted your cycle by adding too many fish at once. but it should restabilize in a few days. You should do large daily water changes until nitrite goes to 0 and stay there.

 

[powerdyne6]

What was your stocking before adding the 7 new fish? You may have disrupted your cycle but it should restabilize in a few days. You should do large daily water changes until nitrite go to 0.

There was no adding of fish.. the 7 all went into the tank together about a year ago. There have been no fish added

 

[Fishmanic]

How often do you feed them? Are you sure you are not overfeeding.

 

[powerdyne6]

How often do you feed them? Are you sure you are not overfeeding.

This was going to be my next question.. How much should I be feeding?

I feed morning and evening.. when the 6 penguin tetras were in the tank I would put enough food to usually last a min or 2. Some of it would sink and the Loach would eat the rest. I have primarily been feeding flakes but have also used bloodworms in the past.

This leads me to another question. When should I introduce a few more of the penguin tetras as the lonely one will probably be a little stressed out by himself. Should I be waiting until I get this under control?

 

[Byron]

The loach needs specific foods tailored to its requirements. Bug Bites is about the best food, and the upper fish will relish this too, so a win-win. Shrimp pellets for the loach, but with only one, don't overfeed.

The loach is a shoaling fish, they develop a social structure within the group when placed in an aquarium, and this is critical to the fish's well-being. I've seen "Tiger Loach" refer to three if not more distinct species, can you tell us which one this fish is? And has the loach been alone for several months (I assume this from your first post)?

To the Penguin Tetras, agree on more (assuming you want this species), a group of 10-12. But also think the nitrite needs to be pinned down. And on that, I still do not see obvious issues. Are you certain you are religiously following the instructions? I know the nitrite and nitrate tests need to be very accurate. If the tap water on its own is zero and the tank water is 1 ppm, this would tend to remove the test being faulty itself (expired reagents), though still anything is possible.

 

[powerdyne6]

The loach needs specific foods tailored to its requirements. Bug Bites is about the best food, and the upper fish will relish this too, so a win-win. Shrimp pellets for the loach, but with only one, don't overfeed.

Will check this out

The loach is a shoaling fish, they develop a social structure within the group when placed in an aquarium, and this is critical to the fish's well-being. I've seen "Tiger Loach" refer to three if not more distinct species, can you tell us which one this fish is? And has the loach been alone for several months (I assume this from your first post)?

I am pretty certain this is the species. It was labelled as a Syncrossus Hymenophysa - Green Tiger Loach at my local fish store.

He has been alone for close to a year

To the Penguin Tetras, agree on more (assuming you want this species), a group of 10-12. But also think the nitrite needs to be pinned down. And on that, I still do not see obvious issues. Are you certain you are religiously following the instructions? I know the nitrite and nitrate tests need to be very accurate. If the tap water on its own is zero and the tank water is 1 ppm, this would tend to remove the test being faulty itself (expired reagents), though still anything is possible.

I am fairly certain I am conducting these tests as per the instructions. This would be my third tank setup although I took a 10 year or so break and have always used the API liquid test kit.

For what it’s worth it says the expiry on my kit is in 2026

 

[powerdyne6]

Like I said yesterday I did a 50% water change.

Just tested the water again

Ammonia: 0ppm
Nitrite: 1ppm (maybe slightly more)
Nitrate: 5ppm (maybe slightlymore)

Should I do 50% water changes daily or is that too much?

 

[Byron]

I am pretty certain this is the species. It was labelled as a Syncrossus Hymenophysa - Green Tiger Loach at my local fish store.

He has been alone for close to a year

This poses a problem. First, here is data from SF:

These loaches are gregarious, form complex social hierarchies and should be maintained in groups of at least 5 or 6 specimens, preferably 10 or more. When kept singly they can become withdrawn or aggressive towards similarly-shaped fishes, and if only a pair or trio are purchased the dominant individual will typically attack the other(s) repeatedly and may prevent them from feeding. That said most botiids require regular contact with conspecifics, a fact exemplied by a number of behavioural rituals which have been recorded consistently in aquaria (see ‘Notes’).​

Second issue, after a year...it may be best to leave the lone loach alone. While it is most probably having stress over this lack of conspecifics, a requirement the fish sees as crucial to life, adding more of them now into this loach's space could be disastrous, especially if this is a male. I am really torn on what to advise. Here's the full entry from SF.

Syncrossus hymenophysa – Green Tiger Loach — Seriously Fish

www.seriouslyfish.com

 

[Byron]

Like I said yesterday I did a 50% water change.

Just tested the water again

Ammonia: 0ppm
Nitrite: 1ppm (maybe slightly more)
Nitrate: 5ppm (maybe slightlymore)

Should I do 50% water changes daily or is that too much?

If nitrite really is present, yes, daily water changes to keep it at zero are indicated. But this is an odd situation, though one that seems not all that uncommon...this is I believe the third active thread about nitrite not really showing any signs of being what one would expect at 1 ppm, all dead fish. Nitrite symptoms including brown (not red) gills (if you can see them under the gill operculum), rapid respiration, and hanging and gasping at the surface. If the fish are acting normal without any of this, I don't see how nitrite could really be at 1 ppm.

 

[powerdyne6]

If nitrite really is present, yes, daily water changes to keep it at zero are indicated. But this is an odd situation, though one that seems not all that uncommon...this is I believe the third active thread about nitrite not really showing any signs of being what one would expect at 1 ppm, all dead fish. Nitrite symptoms including brown (not red) gills (if you can see them under the gill operculum), rapid respiration, and hanging and gasping at the surface. If the fish are acting normal without any of this, I don't see how nitrite could really be at 1 ppm.

The Loach doesn’t bother them up top. If one of the Tetras came down to the bottom he would care and swim toward them. This doesn’t happen that often though.

1 of the Tetras died before I arrived home so I wasn’t sure what had happened. 4 more died within a few hours of me being home that night and I watched this happen. I didn’t notice any brown gills or abnormalities on the fish (although 1 had lost an eye which was weird). The 4 that died I did notice they were quite lethargic and what looked like gasping for air at the surface.

The lone surviving tetra seemed fine that night and has been fine ever since (so far). No signs of brown gills.