# Freshwater Aquariums > New To the Hobby ? >  Loosing fish after being intoduced to an estabished tank

## Not_much_cop

I have an established tank with 2 plecs, 1 catfish, 1 fantail gold fish, 1 fish I have no idea what it is.

I added about 15 or so guppies ranging from very new babies to full adults, and lost some over the last few days, now this I expected as the babies are so small.

I also added 4 platties and lost one after 3 days. this was by no means a small fish, about 1 1/4 inches long.

I also added 6 neons, and have lost 1 a day since, now down to 3. I have been feeding the fish 3 times a day to make sure they are not hungry.

I can not find the bodies, so can only assume they are being eaten over night when the tank/house is dark.

Any ideas, please.

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## Nemo

basiclly u added to much fish at one time and your filter was not able to handle the load. sometimes you get away with adding lots of fishes at one time but it depends on the filter if its a powerfull one then yeh you can overload your tank with no problem at all, but it filter is small and you overload it, then there will be problems, big problems, as it will also effect the fishes already established in the tank.

what you can do now is change 50% water(using dechlorinate water), dont replace clean filter just yet as you wil need the bacteria in there because of the large water change, then just do basic tests for ammonia, nitrates, nitrites.

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## Not_much_cop

I did not think it would overload tank as tank is rather large and I just removed 10 tench and 5 large (very large) gold fish from the tank only a week before hand. Then did a part water change, cleaned filter (External) and added a heater for tropical fish.

Left a week then added new fish.

tank meassures 48 x 24 x 24 inches

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## Nemo

that should have went smoothly as you said u removed large goldfishes from there before it would have already been establised to handle the load, but what you done wrong was clean the filter, killed all the good bacteria. also try putting in a air pump in the tank, maybe oxygen levels are low, as you said u had goldfishes, goldfish hardly need oxygen as they are mostly surface breathers

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## Not_much_cop

Already had a air pump, but put in a bigger one, with a 6 inch long stone so now got a 6 inch wall of fine air bubbles in centre of rear wall. Also had a powerhead pump???? pumps water in and straight back out, which can be adjusted to suck in air with water being pumped back in to create even more air bubbles but got it submerged so that no more are being added. this has been in since I moved in and inherited tank.

I will have to check again tomorrow, to see if another neon is missing.

I think unknown fish may be a "silver dollar", has a body similar to an angel fish but top and bottom points are not so sharp, more rounded off, with a red stripe in body from mid body to tail and a long pointy dorsal fin (top fin) that tappers like a feater and droops backwards slightly, does not point straight up. If that description helps.

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## Nemo

:lol:  you sure your neons aint disspearin in that fishes(silver dollar maybe) mouth  :lol:

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## Not_much_cop

I have added a picture of suspect fish to help identify, can be found at 

h**p://www.fish-keeping.com/forums/gallery/index.php?n=45

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## Nemo

from the looks of it looks like a dangerous fish  :lol: , maybe a type of barb? albino barb? white skirt tetra? cross bred fish of some sort  :lol: , looks too small to eat a neon

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## Not_much_cop

After searching google for the last few hours I believe it to be a Male Long finned Gold Skirt Tetra, it may even be a painted version as mine has black along the leading edge of the dorsal fin.

If anyone knows any better, please let me know.

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## Nemo

yup can also be a white skirt tetra, these are semi agresive fish if kept alone, as i said should be kept in groups.

whats the latest on the tank today mate, any neons missing? or any other fish gone?

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## trinitys_mate

can i ask y you r keeping cold water and tropicals together?

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## Not_much_cop

> can i ask y you r keeping cold water and tropicals together?


No, I had cold water fish, then turned tank into a tropical-ish tank.

The only original fish I had in there were the 2 plecs, and a catfish, before turning it. 

I got rid of all my gold fish except one and all the tench i had in there.
The gold fish is a Fancy Gold Fish, what I would call a Fan tail.

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## trinitys_mate

when you say tropical-ish do you mean u r heating the water or leaving it at room temperature?

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## Nemo

> when you say tropical-ish do you mean u r heating the water or leaving it at room temperature?


 :lol:  he has a heater in there and hes told me on shoutbox he keeps it at 27degrees.

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## Not_much_cop

I have today discovered that it was/is the cat fish that has been eating my guppies and neons.

It too has not been removed from the tank.

Once I get some more plants etc for the babies to hide in, I might return the Gauramis and fancy gold fish, leaving the bard and catfish out in thier own tank.

Thanks for all your help guys and girls.

NMC

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## Nemo

> I have today discovered that it was/is the cat fish that has been eating my guppies and neons.
> 
> It too has not been removed from the tank.
> 
> Once I get some more plants etc for the babies to hide in, I might return the Gauramis and fancy gold fish, leaving the bard and catfish out in thier own tank.
> 
> Thanks for all your help guys and girls.
> 
> NMC


yep return gauramis back in the main tank as gauramis dont eat neons and guppies  :lol:  glad to see ur sorted now. lonely catfish now  :lol:

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## Nemo

hows it going m8

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## Tsia

maybe hes feeding them too much?
Nemo, you told me to only give them a quarter of what I was giving them, and I only fed them twice a day before I reduced it to once a day.

After all they can go over  a week without any food cant they?

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