Ravenes
Fish Crazy
Like the title says I’m worried what happens when you leave the light on for a few hours after introducing fish. I also just turned off the lights
I left the lights on when introducing fish into the tank
- Thread starter Ravenes
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It may increase stress temporarily but your fish will be perfectly okay as long as everything else is good 
Ravenes
Fish Crazy
Ok so when should I do a water change tomorrow?
Whenever you wish!
Ravenes
Fish Crazy
I was also wondering would it stress them out when I add in new water?
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Continue to do your water changes as to your normal schedule. Leaving the light on when adding fish is trivial. In both cases I think that changing things for new fish is more stressful to the fish already in the tank than leaving things normal is to the new fish.
A lot depends on what fish, but most evolved in an ever changing stream or moving water. Change doesn't bother them. The old lights off technique is more to keep the fish already in the tank from reacting too strongly to newcomers. The newcomers are just glad to get out of the bag!
TwoTankAmin
Fish Connoisseur
Fish do not have eyelids. So sudden lights on statles them and may even be a pit annoying or even a tad painful. Think about how your react when you wake up in the dark and turn on a light.
But the first shock is when you open the box or bag where the fish have been in the dark. This startles them. But most tank lights are brighter.
So my practice has been to turn off the light over a tank when adding new fish, I leave them off about an hour and then they go back on. Of course the room is never pitch black anyway. So in the tank there is ambient light.
Next, I pretty much always feed fish soon after they arrive any never longer than that evening. If they have been properly prepared for shipping they have not been fed for several days (unless they are fry). So I know they are hungry.
What I never do is to acclimate fish which have been shipped to me. It doesn't help anything and it is potentially harmful. True acclimation cannot occur in hours, it takes from 1 to 2 weeks and maybe more depending on the conditions.
But the first shock is when you open the box or bag where the fish have been in the dark. This startles them. But most tank lights are brighter.
So my practice has been to turn off the light over a tank when adding new fish, I leave them off about an hour and then they go back on. Of course the room is never pitch black anyway. So in the tank there is ambient light.
Next, I pretty much always feed fish soon after they arrive any never longer than that evening. If they have been properly prepared for shipping they have not been fed for several days (unless they are fry). So I know they are hungry.
What I never do is to acclimate fish which have been shipped to me. It doesn't help anything and it is potentially harmful. True acclimation cannot occur in hours, it takes from 1 to 2 weeks and maybe more depending on the conditions.
Two questions.
Does the advice about feeding also apply to fish you buy directly from an LFS, where presumably they are being fed on a regular schedule?
And when you say that you don't acclimate, does that mean you just put them right in the tank?
I always pour out the bag (temperatures being equal) and put the fish in the tank immediately. No soaking in ammonia in a tiny body of bag water - once the bag is opened the fish have to move.
It doesn't matter whether the fish are in store, wholesaler, Congo or Colombia water. The water doesn't go into my tanks, and the fish do.
It doesn't matter whether the fish are in store, wholesaler, Congo or Colombia water. The water doesn't go into my tanks, and the fish do.
TwoTankAmin
Fish Connoisseur
@sharkweek178
I almost never buy fish from stores and the last time I got them from a pet store was 2001. My last LFS purchase was a very large clown loach about 5 or 6 years ago.
Yes re acclimating. I open the bag and get the fish into clean water ASAP.
I do not do temperatue acclimation either, there is no reason for doing this. Fish live in a temperature range not a single temperature. Once the temperature rises above or below the eaxtremes of the range, it will suffer and if the temperature is enough to kill the fish if it stays there, the best way to save that fish is to put it back into the proper temp. water ASAP. Accilmate it slowly in such a case and you will likely kill it.
I really want to procrastinate, but I keep putting it off..........
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That makes sense. I mean if you think about it. Introducing fish to a fish tank, the coventional wisdom is to put the bag of fish into the tank until the temperature matches. Then add a half cup of tank water to the bag, wait 15 minutes and then test the pH. If the pH doesn't match, then add another half cup every half hour until it does. Then gently remove the fish with a net and place them in the tank. That's what they tell us to do.
Meanwhile, introducing fish to a lake.
Diurnal fish should always be added with lights on (as long as they’re not too bright). First thing they need to do is ascertain that they’re safe, and that there are no hiding predators. Leave the lights on for at least a few hours till they’ve done that. There’s nothing scarier than adding diurnal fish in the dark.
Nocturnal fish should be added with the lights off.
Nocturnal fish should be added with the lights off.
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