Why are my ember tetras so shy?

[Elliott_Fordham]

Hi all,

This is my first post on the forum and I'm starting off with some trouble.

The ember tetras I have in my aquarium are really shy and hide all day until I feed the tank. It is heavily planted with lots of light and a filter with a decent flow. My shrimp seem to be active and so do the snails. My fish just don't swim around like they used to Does anyone know where I may be going wrong?

Thanks and I have listed tank specs below.

Maintenance

50% Tap water change once a week


Equipment
Aquarium = 30x30x30cm Evolution Aqua Aquascaper with glass lid.
Light = Twinstar 300E light - 15 Watts
Filter = 270L/hr corner with spray bar
Heater = Aquael 25 Watt heater.
CO2 = No
Planting = Heavily stocked on plants (foreground, midground and background)
Hardscape = grey mountain stone, manzanita wood

Parameters
Temp - 25 degrees C
Nitrate - 25ppm
Nitrite - 0ppm
Ammonia - 0ppm
pH - 6.8
KH - 6 degrees
GH - Unknown

 

[Tim Harrison]

Welcome Elliot

It could be that your aquarium is perhaps a little on the small size for Ember Tetras. An aquarium with base dimensions of at least 45 ∗ 30 cm or equivalent is suggested. It could also be that the light is too bright, the filter output too strong.

Take a look at what Seriously Fish has to say about Ember Tetras. You may get to the bottom of it yourself. But, if you can post a pic or two of your tank it might help others diagnose what is wrong too.

 

[dw1305]

Hi all,

the filter output too strong

You could try turning the filter off when the light is on and see what happens.

I'm a <"floating plant fan"> for small <"timid fish">, it just makes them feel more secure.

cheers Darrel

 

[sparkyweasel]

They like a dark substrate, or one covered in leaves etc.
They also thrive best in large groups, but on the other hand, you don't want to overstock. How many have you got? Any other fish?

 

[Elliott_Fordham]

Yes maybe it is a bit small which may be causing issues. I will attempt to lower the filter output but unfortunately I can not dim the light. Floating plants maybe a good idea, would they block out a lot of light from my submerged plants? I think the most demanding plant I have is mincrantheum monte carlo. I currently have 7 in a group with 3 cardinals tetras and 2 pygmy corydoras. what floating plants would you recommend?

Thanks everyone!

 

[dw1305]

Hi all,

Floating plants maybe a good idea, would they block out a lot of light from my submerged plants?.....what floating plants would you recommend?

They do, but you can adjust the number to give you enough light at substrate level. If I have a really bright light I just have a thick layerer of floating plants. My "go to" floating plants are Amazon Frogbit (<"Limnobium laevigatum">) as a surface floater and Hornwort (<"Ceratophyllum demersum">) as a sub-surface floater, but <"there are other options">.

I use the health and colour of a floating plant (so not CO2 or light limited) to give me a <"visual indication of nutrient status">. I called this the <"Duckweed Index">, and Limnobium is a nice leaf green colour.

currently have 7 in a group with 3 cardinals tetras and 2 pygmy corydoras.

OK so you can't add any more fish.

Do you feed any live food? I haven't kept Ember Tetras, but Pygmy Corydoras <"really like micro-worms">, and I'd be surprised if the Ember Tetras didn't also like them. Because they are a really small food item, it takes the fish a long time to hoover them all up and that might get them out and about a bit more.

cheers Darrel

 

[Dr Mike Oxgreen]

I currently have 7 in a group with 3 cardinals tetras and 2 pygmy corydoras.

OK so you can't add any more fish.

I’m not so sure it’s as clear-cut as that. This is always going to be a blurry area with different rules of thumb, some more conservative than others, but one such rule that works for small fish is “one centimetre of fish (excluding tail) per litre”. I reckon he’s got about 20cm of fish at the moment, more or less, and that’s in a 27 litre tank (nominally). So in my opinion, with good tank husbandry he could perhaps add 2 or 3 more embers, and this might make the difference to their confidence.

Actually, I would find an alternative home for the cardinals (despite me being a big fan of them). They won’t be especially happy in just a threesome, and being slightly bigger than embers they are probably taking the capacity of roughly four embers.

That said, you do have to consider the fact that a cube-shaped tank has the minimum footprint, so I’d probably not go right up to 27cm of fish. But without the cardinals there is definitely room for 3 or 4 more embers to go with the 7 he’s got without pushing the limit. I also think small tanks look better with just one shoaling species.

I also keep a similar size tank, albeit rectangular. Coincidentally I also have embers and Pygmy cories. There are periods when none of my embers are visible - they are all hiding deep in the undergrowth. But then, five minutes later many of them will be out and about. I just think it might be normal behaviour, and the fish simply make use of the fact that the tank has plenty of hiding places and choose to take an occasional “fag break”. You see pictures of some tanks with virtually no hiding places, and the small fish are out in the open because they have no choice.

I also have Amazon frogbit, which I confine to each end of the (rectangular) tank using threads of polyester tied to suction cups. I have been gradually reducing it because in a small tank its roots interfere with the “picture” of the tank, and the embers often strut about in the bright area in between the rafts of frogbit. So I do think small fish can be acclimatised to less cover, although it helps to start with lots of cover first. Frogbit or hornwort are great for this. I doubt hornwort would survive a postal journey, but I bought my frogbit from eBay and I’m very pleased with it.

 

[sparkyweasel]

Actually, I would find an alternative home for the cardinals (despite me being a big fan of them). They won’t be especially happy in just a threesome, and being slightly bigger than embers they are probably taking the capacity of roughly four embers.

That said, you do have to consider the fact that a cube-shaped tank has the minimum footprint, so I’d probably not go right up to 27cm of fish. But without the cardinals there is definitely room for 3 or 4 more embers to go with the 7 he’s got without pushing the limit. I also think small tanks look better with just one shoaling species.

That sounds like a good plan.

 

[Elliott_Fordham]

Thank you for the suggestions on the floating plants will definitely try some out! Frogbit on ebay looks like a good shout. The cardinals were left over from a tank disaster I had where I lost the majority (heater sticking on) and only have one aquarium. I could give them to my LFS potentially for a discount on some more embers. I tried reducing the flow today and had no luck unfortunately. I think they were even less inclined to come out.

Thanks for the advice everyone

 

[Elliott_Fordham]

Hi All

Just an update - My filter is really quiet so I have never noticed this before but as I was doing some maintenance today I realised that my filter quite heavily vibrates my tank. It's a corner filter and cost about £10 so nothing expensive. Could this vibration be causing my fish trouble? Let me know what you think and also if you know of any discrete internal filters that would not vibrate as much could you post them in here.As a side note I can't have a canister because I have to have a lid as the room I have the tank in will get damp without one.

Thanks

 

[alto]

my filter quite heavily vibrates my tank.

most fish are sensitive to vibration so I would explore this

I often use an Eheim Mini Up filter in my 30C BUT I seldom keep fish in these tanks - and I just touched the glass and can feel the hummmmmm

Can you not just do some cutouts for filter inlet/outlet - obviously this would require some preparation

 

[Elliott_Fordham]

Yes I will investigate this as I believe it is a possibility that the vibration is causing the timidness of my tetras. I have a glass lid and to do cut outs would require various pieces of equipment that I don't own I might however try my cannister with the lid off as it's summer now and the walls of the room are warmer.

Thanks for the advice

 

[alto]

As you’ve the canister filter already, easy to try this - cling film makes a decent temporary lid

Can you slide the glass forward/sideways a bit to allow room for the canister - use some self stick tabs to keep the glass in place, sorry no idea of the proper name but you can see them in Jurijs mit JS video DOOA 20 x 20 x 20 @3:25

 

[dean]

I’d say you group is too small for them to feel secure
Especially as you have small numbers of two other species that will also feel insecure

My suggestion would be to go with just one species in a small tank then use shrimp and snails as the clean up crew


Sent from my iPhone using Tapatalk

 

[Elliott_Fordham]

Update: I have switched to the canister filter and managed to secure the lid in a slightly different position. It's is helping with algae but fish haven't really changed their behaviour. I think potentially the light is just to bright for the lil guys. Gonna order some floating plants off of Ebay and when I'm able to go to the LFS return the cardinals and but a couple more embers and shrimp.

Thanks all

 

[Dr Mike Oxgreen]

I’m not convinced that the bright light is the issue. I have seen mine all out and playing boisterously in the brightest part of the tank, where only an hour or two earlier they were all tucked away.

In fact, I think I have noticed that they become bolder and more active as the lighting period continues. I am wondering if this is actually an oxygenation issue, so I’ve ordered another electronic timer so I can run an airstone overnight. I don’t think it’s a CO₂ issue, because I’ve seen them at their most active when CO₂ is very high (drop checker very light green).

 

[Dr Mike Oxgreen]

I’ve just looked up the spec of your light.

I acknowledge that lumens are not the ideal measure, but as is often the case it’s all we’ve got. Your light is 1,100 lumens, giving about 40 lumens per litre. This puts you on the cusp of high lighting.

But... I’ve got about double that, around 80 lumens per litre, and my tank is shallower. Some might say that’s too much, and they might be right - but as I say I regularly see my embers frolicking about in the brightest part of the tank. But I’m suspecting I only see this towards the end of the photoperiod.

Purely from an algae point of view, I’d say you’ve got too much light, given that you’re not using CO₂ - but I’m not convinced this is the problem from a fish behaviour point of view.

Now in my tank, I am using generous CO₂ and therefore photosynthesis is somewhat turbocharged. Towards the end of my lighting period I get a lot of bubbles on my plants and rising up from them. This indicates that the water has a high oxygen content, but it takes hours to get to that state - maybe four or five hours. Perhaps this indicates that my water is rather low on oxygen at the start of the photoperiod (it is densely planted, and the plants are net consumers of oxygen overnight), and this is why I intend to start experimenting with an airstone overnight.

I just wonder, if I’m right about low oxygen in my tank, maybe that’s your issue as well? Can you reposition your spray bar or lily pipe to give stronger surface agitation, and/or experiment with an airstone?

 

[Dr Mike Oxgreen]

Something else you could try regarding oxygen is turning the temperature down a bit. I’ve got my embers at 23°C and they seem perfectly happy at this temperature. Is it worth knocking your temperature down a degree or two to further test the oxygen hypothesis, in addition to increasing surface movement?

 

[Dr Mike Oxgreen]

Apologies for a further reply!

As I sit here now, my embers were hiding away at the start of the photoperiod. But now, four and a half hours later, the embers are out and about. The ballsy males are flexing their muscles, and there is some jostling for rank. All normal stuff. They are not schooling tightly, which to me indicates stress in most species. Meanwhile, bubbles of oxygen are rising from the hairgrass and HC Cuba, and starting to accumulate on the Hottonia palustris and Rotala walichii.

So once again, the embers’ activity correlates with oxygen. CO₂ is pretty high, with a lime green drop checker.

 

[Dr Mike Oxgreen]

Well, I set up an air pump and stone yesterday, intending to switch it on before I went to bed - but I forgot!

However, I did switch it on for an hour and a half this morning, before the CO₂ switched on.

And the difference in the embers’ activity level is remarkable. Right from the beginning of the photoperiod they’ve been moderately active, where before I’d expect them to be hiding away until well into the photoperiod. And this is with only 90 minutes of aeration - I’m excited to see what things might be like if I aerate for a longer period.

I’ve now got another electronic timer and have programmed it to power the air pump overnight until the morning.

So it’s early days yet, but it does appear that my heavily planted tank might have been oxygen-depleted overnight. I really wonder whether this might also be @Elliott_Fordham ’s problem as well.

I strongly recommend experimenting along similar lines: have an air pump come on overnight, switching off before the CO₂ comes on. With luck, @Elliott_Fordham might be pleasantly surprised by the change in the embers’ behaviour!