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Tiny fish attacking bigger one

11 replies

NHSisfubar · 03/07/2015 02:43

DP has an old goldfish and we recently bought a new much much smaller one to go in with it.
The new one is literally a quarter of the size or even smaller. The old one has a dodgy swim bladder but I had been feeding it frozen peas and since DP cleaned the tank it had looked much perkier and spending less time upside down hence buying the new one.

I have just checked the tank before going to bed and caught the small fish literally trying to eat the big one who had got jammed against a plant at the bottom of the tank. The poor old one has blood spots around the bottom of his belly and the new one keeps going for him. I had seen it doing some fin nipping but this is quite bad and I don't know what to do. In all honesty the old one is probably on its way out and has been for a while but I can't just leave him to get cannibalised by the new one. I will try and get a small basket to keep them separate tomorrow but what else can I do? We don't have another tank. Help!

OP posts:
NHSisfubar · 03/07/2015 03:22

Update; managed to find a piece of plastic mesh which I have rolled into a tube that fits in the opening of the tank (biorb) so little one is inside the mesh tube around the pump and big one has the outside against the glass. Also noticed they have what looks like the start of white spot on fins. Me and fish; disaster.

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EauRouge · 03/07/2015 08:23

One problem I can see here is the biorb- entirely unsuitable for goldfish and your DP's one is lucky to have survived this long. Adding a new fish has probably caused an ammonia spike which is what may be causing the blood spots. Also overcrowding can create aggressive behaviour. What you need to do is remove the new fish ASAP and move it to another tank. I would leave the old fish there, the shock of a move would probably kill it. Have you got a water testing kit? The white spots could be ich- does it look like little grains of salt?

Apologies if I'm being abrupt, no caffeine yet and DD1 kept me awake last night.

NHSisfubar · 03/07/2015 23:09

Hi, thanks for your reply; sorry for delayed response - today has been non stop! My temporary mesh barrier is working well and I have been offered a free tank by my boss so can separate them when I get that. Yes I think it is ich but DP has some treatment stuff he found so I will sort that tomorrow. Why is the Biorb not suitable? Apparently he had 3 in there for 7 years and this one is the last survivor. I do think it's quite small but assumed there was something better about the filtration or whatever that was different from a normal tank? Appreciate the advice thanks!

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EauRouge · 04/07/2015 09:04

This is a good guide to goldfish size and life expectancy. It's about 15 years for fancy goldfish (fat, round ones) and 20+ years for common goldfish (normal shaped ones). Unfortunately this isn't seen very often because shops don't sell suitable tanks or warn people about how big goldfish get. Because if they did, no one would buy goldfish and they bring in a lot of money.

Biorbs have some clever marketing (and there's no denying they look nice from a design point of view) but their filters are actually not very good. Goldfish are messy buggers and need some pretty serious filtration to keep them clean. A rectangular tank with an external filter is much better.

Glad you're getting the ich sorted, hopefully both the fish will be OK :)

NHSisfubar · 05/07/2015 11:55

Right; I have done the treatment yesterday and both fish are looking pretty awful. Both are now developing blood spots/red patches so am now thinking that the small one didn't cause this. The big ones fins have gone all straggly and both fish look pretty listless. I did a 50% water change as well but doesn't seem to have made any difference and the white spot still seems to be there (although not sure how long the stuff takes to work/spots disappear?). Could the warm weather be exacerbating the issues? Thanks

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EauRouge · 05/07/2015 13:29

Have you tested the water yet? Ammonia in the water can sometimes cause bloody streaks.

NHSisfubar · 05/07/2015 14:49

No I don't have a kit and was hoping the treatment would help issues along with water change. I can't see the big one lasting but would like to save the newer one. Will try and get a kit tomorrow if they last that long. Thanks

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bowsaw · 06/07/2015 11:26

50% water change will be a lot of stress on them, is it straight from the tap?

EauRouge · 06/07/2015 12:50

Water changes should not cause stress if the water is the same temp and pH. If there is ammonia in the water then doing a large water change is essential to make the water safe for fish. It should also be conditioned to remove chloramine and heavy metals.

NHSisfubar · 06/07/2015 20:08

Haven't managed to get a testing kit as couldn't get to a shop due to work but the smaller one is dead tonight. Am amazed the other one is alive; the smaller new one seemed quite perky yesterday after water change and white spot treatment. It was tap water but I left it out for about 18 hrs before adding to warm up and de chlorinate. Obviously no good. Shame as the little one was lovely

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EauRouge · 06/07/2015 21:20

Sorry about little fish :(

Leaving the water to sit used to work when water companies used chlorine, but now chloramine is used because it is more stable so doesn't just dissipate like chlorine does- this makes water safer for us to drink but not so great for fish. So you need to use a dechlorinating treatment to remove it from tap water.

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