Can the light be too strong for the fish

[DGJ]

Hey Everyone,

Can the stock lighting tube be too bright for the fish?

I have 7 Congo Tetra's that are always down at the bottom/back of the tank when the light is on, when I turn it off they are around the middle of the tank and then as soon as I turn it back on then shoot straight back to the bottom.

Does this mean the light is too bright for them? The Goldfish and Koi seem happy as larry in there.

If it is too bright, whats the simplest/cheapest way to reduce the power?

The below is the light details from the website

Brilliant luminosity and excellent plant growth are what you get with the state-of-the-art Multilux LED lighting technology from JUWEL. The replaceable 590 mm DAY and NATURE LED tubes create an optimum light spectrum, while saving up to 50% of energy in comparison to T5 at the same time.
The MultiLux LED lighting system for the TRIGON 190 LED means that you can work on your aquarium in comfort, even when the lighting is switched on.
The ultrasound-sealed light unit is 100 percent waterproof and fulfils the stringent European safety standards.

 

[PlasticGalaxy]

Congo tetras are tropical fish, I'm pretty sure. Meaning they shouldn't be with coldwater fish like koi and goldfish. It could be down to the temperature being too cold for them.

 

[Byron]

Can the stock lighting tube be too bright for the fish?

I have 7 Congo Tetra's that are always down at the bottom/back of the tank when the light is on, when I turn it off they are around the middle of the tank and then as soon as I turn it back on then shoot straight back to the bottom.

Does this mean the light is too bright for them? The Goldfish and Koi seem happy as larry in there.

If it is too bright, whats the simplest/cheapest way to reduce the power?

Responding to the strictly light-related points/questions here...yes, overhead tank lighting can be too bright for most of our fish that are forest fish (Congo Tetras are such). The solution may be to reduce the lighting (this is where high-tech planted tanks fail for fish, the light is just too intense for most of the species), but if the light is not overboard, using floating plants like Water Sprite, Frogbit or Water Lettuce usually solves the problem. My group of Congo Tetras lived in a 4-foot 90g tank and they all swan mid-level, and shoaled together at that level. Periodically I had to thin out the Water Sprite, and just two plants would easily grow to cover the surface completely, and the adventitious plantlets on the alternate fronds (leaves, but this is a true fern) only added to the the thickness, but when removed from the parent plant and the latter discarded solves this. But when I did this thin out, the entire group of Congos moved down and remained there for how ever many days it too for the surface plants to cover enough of the surface that the fish felt comfortable and safe moving up. This is an internal instinct to avoid surface predation from birds, etc, so it is not going to "go away" and we must provide the safe haven.

Fish have a strong sensitivity to light. Not only through their eyes, but every external cell is light sensitive, and much more than it is with humans for example. It impacts many aspects of their lives.

BTW, I agree goldfish and koi should never be housed with tropicals.

 

[DGJ]

Ah the guy in the shop said it was fine for them, he also said I could stock Yoyo loaches and I was goin to go back to get some this week, is that also incorrect?

I will need to look at getting a different tank, however I'm not sure it's the temp as they are swimming about in the top 1/3rd of the tank with no light on?

 

[DGJ]

Thanks both for the replies, looks like I will need to invest in a new tank and move them as soon as I get it cycled, will they be ok in the tank for a few weeks until the new one is bought and cycled?

 

[Essjay]

Several years ago I bought a shoal of Trigonostigma espei, a close relative of harlequin rasboras. They spent all their time huddled in the back corner of the tank. Then I read about floating plants, so I bought some water sprite. The fish started swimming around more, but only under the plants. As the plants grew and covered more of the surface, they swam further and further into the tank.

It sounds as though your congo tetras are reacting similarly, only swimming downwards rather than huddling in a corner.


But I think goldfish like to eat plants, so getting another tank, one for the coldwater fish and one for tropicals, and getting floating plants for the tropical tank should help the congos.


When you get a new tank, take some media from the current one to jump start the cycle.

 

[PlasticGalaxy]

Ah the guy in the shop said it was fine for them, he also said I could stock Yoyo loaches and I was goin to go back to get some this week, is that also incorrect?

I will need to look at getting a different tank, however I'm not sure it's the temp as they are swimming about in the top 1/3rd of the tank with no light on?

Thanks both for the replies, looks like I will need to invest in a new tank and move them as soon as I get it cycled, will they be ok in the tank for a few weeks until the new one is bought and cycled?

Yeah, both are incorrect. It's best to never listen to the guy in a store, even if they look like they know what they're talking about! They usually just act like yes-men to get you to buy more stuff.

I'd honestly see if they'll take returns and give refunds, because turning up the temperature will upset the goldfish and koi, but keeping it low will stress the loaches and tetras. It's a tricky situation.

You could buy a large plastic tub for now, and fill it will tank water and use a sponge filter or similar as a make-shift tank for the tetras and loaches if you decide to keep them.

 

[Byron]

I agree with others here; first task is the get some floating plants (easy one if a local store carries any), and decide on which fish have to go (store return, or another tank, or another aquarist). I don't know the dimensions of this tank, but keep in mind that the Congo Tetras need a 4-foot tank for a group, as they will grow to 3-4 inches and can like to swim "lengths" when they are settled. The YoYo Loaches could work with Congos, depending upon the species (common names are frequently misleading, and esp with this loach) and the 4-foot tank is needed for them, so this should work together in such a tank.

The goldfish and koi need at least this large a tank for themselves, perhaps more depending upon the size they attain; one of our goldfish expert members may have more on this.

 

[Colin_T]

The goldfish and koi will be fine with the congos for a while until you can organise another home for them. I will say that koi carp can grow to 3 feet long and then some so you might want to find a pond for them or return them.

Depending on the goldfish, some are fine in aquariums and others should also be in ponds due to their adult size. Single tail goldfish (common, comet & shubunkin) can get to 8-10 inches in body length (this does not include the tail). Double tail (fantail) goldfish can get to 6 inches body size (not including the tail). It takes a few years for them to get this big but they can grow quite large.

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Put some floating plants in the tank to give the congos some security. You can use real live plants like Water Sprite (Ceratopteris thalictroides/ cornuta), or you can buy plastic floating plants.

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LIGHTING TIMES
Most aquarium plants like a bit of light and if you only have the light on for a couple of hours a day, they struggle. If the light doesn't have a high enough wattage they also struggle. Try having the tank lights on for 10-12 hours a day.

If you get lots of green algae then reduce the light by an hour a day and monitor the algae over the next 2 weeks.
If you don't get any green algae on the glass then increase the lighting period by an hour and monitor it.
If you get a small amount of algae then the lighting time is about right.

Some plants will close their leaves up when they have had sufficient light. Ambulia, Hygrophilas and a few others close their top set of leaves first, then the next set and so on down the stem. When you see this happening, wait an hour after the leaves have closed up against the stem and then turn lights off.

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TURNING LIGHTS ON AND OFF

Stress from tank lights coming on when the room is dark can be an issue. Fish don't have eyelids and don't tolerate going from complete dark to bright light (or vice versa) instantly.

In the morning open the curtains or turn the room light on at least 30 minutes (or more) before turning the tank light on. This will reduce the stress on the fish and they won't go from a dark tank to a bright tank instantly.

At night turn the room light on and then turn the tank light off. Wait at least 30 minutes (or more) before turning the room light out. This allows the fish to settle down for the night instead of going from a brightly lit tank to complete darkness instantly.

Try to have the lights on at the same time each day.

 

[Essjay]

The tank here is a Juwel Trigon 190 (from another thread). This is a triangular tank. Dimensions in this link

JUWEL Aquarium | Trigon 190 LED | purchase online

Trigon Line LED - Trigon 190 LED. JUWEL Aquarium

www.juwel-aquarium.co.uk

 

[Byron]

The tank here is a Juwel Trigon 190 (from another thread). This is a triangular tank. Dimensions in this link

JUWEL Aquarium | Trigon 190 LED | purchase online

Trigon Line LED - Trigon 190 LED. JUWEL Aquarium

www.juwel-aquarium.co.uk

Thanks essjay. The larger tank here might suit the Congos, certainly the loaches (these need swimming space, but don't care if it is a straight length or just "space" as would seem to be provided here).