Mysterious cause of stressed fish-HELP!!!

[justinbudyk]

Hi everyone,

So this is going to be a lengthy explanation but the gist is this: I have a 5 gallon freshwater fish tank that I've had for about 3 months. In it I have all the original fish that I got with the tank setup: 3 neon tetras, 3 rummy nose tetras and a yellow gourami. They have been happy and healthy up until the last week or two when they ALL have started having weird symptoms such as: losing all of their colour, becoming erratic (darting, shivering, twitching), separating in the tank, drifting backwards etc. Basically they are stressed. But the weird thing about it is that it only happens at a certain time of day; that is, from about 9 or 10pm till the early morning (at least as late as 4am). They are perfectly fine and happy again when I wake up in the morning.

It is also worth mentioning that I have 5 small cherry shrimp and a handful of snails in there that are NOT affected. I've been told that the shrimp are more sensitive to water quality changes than my fish so it's bizarre that they have been unaffected.

I know it is something in the water because when I do a water change they return to normal again. This is NOT a behavioural response due to one of the fish bullying the others. I have taken a water sample into a reputable, knowledgeable aquarium specialist where he tested for: Ammonia, Nitrite, Nitrate, pH, Hardness (Carbonate and General) and Copper. All the tests came back perfect. Additionally I make sure to always treat water I add to the tank to remove chlorine/choloramine and add a standard biological aquarium supplement, as well as a supplement for the plants. I have LOTS of plants in there as well as rocks (no coral, but a few small shells as well) so oxygen is not an issue (they aren't gasping at the surface anyways). I have changed the carbon filter recently, keep the temperature stable at 78F and feed them moderately once per day with crushed tropical fish flakes. I have also switched their feeding and light (when I turn on/off their light; usually it's on ~12 hours/day) schedules to see if there is a change in behaviour or time when they become stressed. This hasn't changed anything, they still always become stressed at the same time and in the same way.

There is also no way that anything is getting into the water from air fresheners, etc. etc. The onset of the symptoms wasn't correlated with any changes to their habitat (eg. addition of rocks), the fish/invertebrate community, or really any other changes; it's essentially come out of the blue.

My best guess is that there is some biological process happening at night that results in a release of some sort of toxin into the water, and that it is gone by morning. Does anyone have any idea of what this might be or what sort of tests I can do to isolate the problem? I'm pretty desperate here haha, I don't want my fish babies to be stressed and die!!

You all are awesome, thanks so much in advance,

Justin

P.S. I will attach a file tonight showing the stress response.

 

[jonny-5]

You could do with investing in a water test kit to start with to see whats happening.

They may be stressed due to the lights being on for 12 hours, Maybe try 10 hours.
Also depending how the light comes on/goes off can stress them to, The main room light should be on a little before the aquarium light turns on. Also the room light should be on when the light unit is switched off, Then they wont be just left in total darkness straight away. Otherwise this can make them stressed, In the fishes natural habitat light does not simply just switch from light to dark.
I know the advice sounds simple but it is almost always overlooked & it does help.
Another thing is the food, if you are only giving flake they will get very bored of it & the diet plays a huge part in all fishes well being so that also can cause stress, Loss of colour etc etc.
Try some frozen Bloodworms,Brine shrimp or Bug bites, Just something different really.
5 Gallon is too small for a Gourami & Rummy Noses which both need lots of swimming space. This will be a major stress factor
The cycle in your tank wont be stable enough either cos its so small. You will have spikes of Ammonia & Nitrite, So this could relate to the strange behaviour you are seeing

 

[Naughts]

If you use CO2 you can get reduced oxygen at night.

Neons in particular lose colour at night and will regain it within half an hour in the morning. Fish will also drift and separate when sleeping. Jonny explained gradual lighting changes reducing stress which will probably solve the darting and erratic swimming.

But the bottom line is 5 gallons is too small for any fish except a single betta splendens. Honey gourami need 10 gallon minimum, neons 20 gallon and rummies 40 gallon.
Check out https://www.seriouslyfish.com for fish requirements, upgrade the tank and stock accordingly.

 

[ClownLurch]

Im no expert by any means but everything I’ve ever read tells me a 5G is far too small.

 

[justinbudyk]

@ClownLurch @Naughts @jonny-5

Thanks for responding!! I'm going to address all your suggestions here.

1. Light: I will try and cut back on the light to 10 hours and have a more gradual dimming of the tank, that's a great suggestion! That being said, I'm not sure why this would suddenly start effecting them after following 3 months of the same routine.

2. Food: I will try and mix up the feed a bit!

3. Tank size: I definitely understand everybody's concern with the tank size. However, to be devils advocate, I have accomplished aquarium friends with tanks half the size and with far more fish, shrimp, plants etc. and the (same species) of fish are thriving! And while you might be right that the tank should be bigger, why would this result in the bizarre behaviour and physical changes at a certain time of night? It just doesn't add up to me.

Does anyone have any thoughts on the biological (or abiotic) process/toxins or hypothesis? I'm fairly sure that it's something in the water that is making them get stressed because if I do a water change, they regain their colour and start behaving normally within 30 minutes... The fact that they get stressed at the same time of night regardless of what is happening with the light and food regime is worth considering I think.

Thanks again for your help!

Justin

 

[jonny-5]

As i explained the bizarre behavour could be down to unstable tank water parameters, a 5 Gallon has no room for error, By error i dont mean you are doing anything wrong, I mean the whole Nitrogen Cycle process. In that size of tank you will almost certainly get spikes of Ammonia,Nitrite & Nitrate regardless of how established the tank is.

Darting, Twitching & Shivering are a clear sign something is very wrong here.
In the original post you answered your own question......

My best guess is that there is some biological process happening at night that results in a release of some sort of toxin into the water, and that it is gone by morning. Does anyone have any idea of what this might be or what sort of tests I can do to isolate the problem?

 

[jonny-5]

The larger the tank the more room for minor things to go un noticed. Like an Ammonia spike in a 5 Gallon will be deadly, The same spike in a 10 or 20 Gallon will be more forgiving due to the fact there is more area & volume of water to dilute the concentration.
Also i noticed you said the tank has been running a few months with no problems, The spikes may be tolerated by any fish at first but if it keeps happening the fish are going to be weakened by the constant water changes & will cause undue stress & illness.

 

[justinbudyk]

@jonny-5

Hmm ok that makes sense about the fluctuating levels due to the small tank. But what about the fact that I've been checking the Ammonia, Nitrite and Nitrate levels with my at-home test kit (just the dip strips) and I took a water sample to my aquarium expert and none of these compounds were found? There weren't even trace levels. Could it be something else biological? And if so, how can I determine what it is? I guess what I'm saying is, what should I do from here to try and resolve the problem?

Thanks again!

Justin

 

[jonny-5]

The levels of Ammonia, Nitrite & Nitrate can change in a few hours,They can be fine all day then a few hours later the levels could be high,Then levels return back to normal This is why its called a spike.
So unless you are testing every few hours it will go un noticed

Clearly the fish are not happy & if you say the water parameters are correct then i would put it down to tanksize,diet or spikes in cycle

The dip strips are ok for a quick test but not really accurate, Liquid test kits will give you a more accurate reading & lasts 5 times longer for the slightly higher cost

 

[justinbudyk]

The levels of Ammonia, Nitrite & Nitrate can change in a few hours,They can be fine all day then a few hours later the levels could be high,Then levels return back to normal This is why its called a spike.
So unless you are testing every few hours it will go un noticed

Clearly the fish are not happy & if you say the water parameters are correct then i would put it down to tanksize,diet or spikes in cycle

The dip strips are ok for a quick test but not really accurate, Liquid test kits will give you a more accurate reading & lasts 5 times longer for the slightly higher cost

Ok, thanks so much for all your advice!! All the best.

Justin