What the heck is going on in my tank?

[eschaton]

Hey guys,

I've been in the hobby off and on for over a decade. I don't have any home tanks, but I have a 40 gallon planted tank in the office which I hadn't been properly maintaining for awhile due to health issues in my family. It had a low level of stocking (a mixed school of boraras, a single ember tetra, aquatic dwarf frogs, Amano shrimp, and some snails) for a year or two, with nothing new introduced. I decided since I had more free time to start sprucing up the tank again. I swapped out the decade-old filter for a new model with higher flow, replaced the failing heater, and sucked out a lot of the mulm that had accumulated over the years. Then I started restocking the tank slowly over a period of a few months. I added, in a series of steps...

6 Corydoras Sterbai
3. Khuli Loaches
9 Beckfordi Pencifish (initially added six, but ended up with mostly males who pestered the few females, so I had to get more females to balance out)
12 Espei raspbora
5 Ember Tetras

(plus some cherry shrimp and more types of snails - no issues here).

Note that all of the fish I added were from a local fish store who captive breeds them.

The tank is heavily planted, so I don't see some of the fish on a regular basis. I was also basically out of the office for two weeks and someone else was taking care of the tanks. When I came back, they mentioned the corys were mostly gone. The last two I could see were very thin, swam around the tank, but showed no interest in eating. I didn't get a chance to do much.

Soon after I noticed that the Espei school was beginning to thin. I started putting them in isolation as I noticed symptoms (mostly just paler color, odd behavior, and a "clouidy" look to the interior of the body. I have some Metronidizole on hand (although its years old, and I'm unsure of the effectiveness), and began dosing the tank with it. I've also put some Melafix in, figuring it couldn't hurt. Could my old fish - who had been alive in the tank for years without problems - have been carriers of parasites they passed on to the newcomers? Or

This morning, though, a more acute issue arose. The Beckfordi pencilfish were acting weird when I first came into work, hanging out in groups near the surface rather than darting around the tank like they were a few days ago. Then I noticed a shrimp was starting to eat one that had died suddenly (still had full normal coloration). I found another one which suddenly died in the tank as well. All of the pencilfish were breathing rapidly and acting distressed, but no one else was.

I knew I needed to do something to help the tank immediately so I did the following.

1. 20% water change (I would do more, but it's not feasible during work time to spend that much time on the bucket brigade).
2. Turned down the heater, figuring it would help oxygenation.
3. Immediately cleaned out the filter (which hadn't been cleaned in a month) in order to improve flow.
4. Tested my water parameters, which were all fine (zero ammonia/nitrite, low levels of nitrate, neutral PH)

No more pencilfish have died, but they're still acting oddly.

Anyway, I don't know what to do now. Obviously whatever is happening with the pencilfish aside, there is some parasite in my tank, whether one of my older fish was a healthy carrier or one of the new fish introduced it. I cannot and will not introduce more fish into the death trap of my tank. I can't dose with copper given all the shrimp and snails in the tank. And setting up a set of QT tanks really isn't feasible. What do people suggest?

 

[Byron]

There are several possibles to explain this, and I am no expert in disease so I will confine my remarks to general observations/suggestions.

First, unless you are near certain of a specific disease, it is best not to add treatments (meaning, medications, substances). These stress out fish, no matter what they are nor the issue, so unless the treatment has an effective role it is only making things worse for the fish.

Major water changes are usually the most effective thing you can do. However, one caveat. If things have been let go for longer than usual, the buildup of organics in the substrate and the filter will likely cause a significant deterioration in water quality, and produce ammonia. At the same time, the pH may lower. A pH below 7 is acidic as you probably know, and in such water ammonia changes to ammonium which is basically harmless (unlike ammonia). A water change introducing basic water (pH above 7) may cause a shift in the pH in the tank, and if it rises above 7 the ammonium changes back into toxic ammonia rapidly. Testing the aquarium water for ammonia, nitrite, nitrate and pH prior to taking any action is essential. And obviously knowing the pH of the tap water. With these results, you can proceed accordingly; major water changes of even 75% will always benefit except for this pH aspect. Now, obviously this issue will cause an immediate problem, not one that turns up weeks later, but there can still be some aspect relevant. Something to keep in mind.

Disease can remain present without external signs, only to infect new fish. Parasites like ich and velvet can do this. Disease can also be introduced with new fish.

This could be a water issue, not any disease, or it could be disease, or it could be both. Once the parameters (pH) are stable, larger more frequent water changes will definitely help, whatever the issue, and may on their own resolve things. Sometimes happens.

Nitrate...always give us the numbers; "low level" to one person may be anything but to another. Nitrate does impact fish just as ammonia and nitrite, only nitrate is slower and depends on the level, exposure time, and species. Generally, it weakens all fish, and that is always an opening for other disease issues as it causes stress. Water changes will reduce nitrates (unless the source water has nitrate present...?).

Aside from what I said initially about adding medications, etc...metronidazole can be effective for many internal protozoan and metro is usually safe for most fish, certainly those mentioned here. Add it to the food, it is far more effective, and feed only this food for a week to 10 days.

Byron.

 

[eschaton]

As an update, a few hours ago there were still six pencilfish (two died suddenly and were removed from the tank, one was missing). While they are still breathing rapidly, most of them have come down from the water surface and are swimming around the tank now.

First, unless you are near certain of a specific disease, it is best not to add treatments (meaning, medications, substances). These stress out fish, no matter what they are nor the issue, so unless the treatment has an effective role it is only making things worse for the fish.

I can say with some certainty it isn't ich, velvet, pop-eye, dropsy, or anything else of that sort. As I said, for the most part the only symptoms have been paler coloration, lethargy, and lack of interest in food, which are pretty generalized and can mean a number of different internal parasites.

Major water changes are usually the most effective thing you can do. However, one caveat. If things have been let go for longer than usual, the buildup of organics in the substrate and the filter will likely cause a significant deterioration in water quality, and produce ammonia. At the same time, the pH may lower. A pH below 7 is acidic as you probably know, and in such water ammonia changes to ammonium which is basically harmless (unlike ammonia). A water change introducing basic water (pH above 7) may cause a shift in the pH in the tank, and if it rises above 7 the ammonium changes back into toxic ammonia rapidly. Testing the aquarium water for ammonia, nitrite, nitrate and pH prior to taking any action is essential. And obviously knowing the pH of the tap water. With these results, you can proceed accordingly; major water changes of even 75% will always benefit except for this pH aspect. Now, obviously this issue will cause an immediate problem, not one that turns up weeks later, but there can still be some aspect relevant. Something to keep in mind.

I checked the PH, and it was around 7.6. I was honestly surprised it was so high, because I know long-term planted tanks tend to drift towards acidity, even if CO2 isn't being injected.

Nitrate...always give us the numbers; "low level" to one person may be anything but to another. Nitrate does impact fish just as ammonia and nitrite, only nitrate is slower and depends on the level, exposure time, and species. Generally, it weakens all fish, and that is always an opening for other disease issues as it causes stress. Water changes will reduce nitrates (unless the source water has nitrate present...?).

Nitrate was at 5 PPM. My experience has been nitrate tests can be very unreliable - particularly in older test kits due to the settlement out of the catalysts. However, as a planted tank, one would presume the plants would hoover much of the nitrate up over time.

 

[Essjay]

Many years ago, before I knew any better, I had a sickly honey gourami and had no idea of the cause. So I added Melafix and Pimafix at the recommended doses, the instructions saying they could be used together. I also had a shoal of Beckford's pencilfish in the tank. After adding the -fixes I went to watch a 45 minute television programme, and came back to find all but one pencilfish dead. The last one was thrashing about and died shortly afterwards. I don't know if it was Melafix or Pimafix or the combination of them that killed the pencilfish but I would never use either again in a tank with these fish.

This could be the cause of the problems with your pencilfish on top of any problems affecting the rest of the tank.

 

[Byron]

Essjay has a good point. Years ago I tried these two products, though not together, on general advice they would help the unknown issue. My fish reacted though much more slowly, after a day or two, but it shows how these things can affect fish, and different fish differently. Such general products rarely if frankly ever work because they are not strong enough to target specifics. "Cures" from using such products are probably more likely the result of the fish overcoming the problem or an improvement in water conditions. As another members has written elsewhere, water quality is a major factor and can often work on its own.

Some will be tired of reading this again, but it must be kept in mind. Every substance added to the tank water ends up inside the fish, in the bloodstream and internal organs. Aquatic organisms are so very different from terrestrial in this respect. Most if not all of these substances will have some impact on fish.

To your nitrate at 5 ppm,, that is nothing to worry about so another issue out of the picture. Nitrate of course is directly related to the fish load (resulting organics), and planted tanks tend to be naturally lower. This is not generally because the plants are "hoovering" the nitrate, but more because they are using so much of the ammonia/ammonium. Most aquatic plants prefer ammonium as their source of nitrogen, so they rapidly take up ammonia/ammonium. Little is left for the Nitrosomonas bacteria, which means less nitrite, so less Nitrospira bacteria producing much less nitrate. Some plants do take up some nitrate too, it is just normally less this direct way. And of course there are de-nitrifying bacteria in a healthy substrate using nitrate to produce nitrogen gas that dissipates back into the atmosphere and others resulting in oxygen production.

So I guess all this leaves us with a possible pathogen or internal protozoan and/or reaction to chemicals/medications.

 

[eschaton]

Many years ago, before I knew any better, I had a sickly honey gourami and had no idea of the cause. So I added Melafix and Pimafix at the recommended doses, the instructions saying they could be used together. I also had a shoal of Beckford's pencilfish in the tank. After adding the -fixes I went to watch a 45 minute television programme, and came back to find all but one pencilfish dead. The last one was thrashing about and died shortly afterwards. I don't know if it was Melafix or Pimafix or the combination of them that killed the pencilfish but I would never use either again in a tank with these fish.

This could be the cause of the problems with your pencilfish on top of any problems affecting the rest of the tank.

I wondered if maybe the Melafix played a role, since they didn't start dying until after I added it (at the correct dose) into the tank. However, this morning even before I added the Melafix they were acting a little odd (hovering in groups near the surface of the tank, as if oxygen deprived) so I figured it was just coincidence. Searching online, it seems not. I'm going to do some more water changes.

Edit: Out of my original shoal of nine pencilfish, four seem to have survived the crisis and are acting normally. Two more is clearly still alive, but still acting oddly. Another two died, and presumably the last one also perished but fell somewhere in the rear of the tank where I cannot see him.