How Many Goldfish in a Bath?

[abrogard]

We have an old cast iron bath in the garden and we've put water and little goldfish in it.

It's about 200 litres which is about 50 gallons US. That's the water they're swimming in, not the total available volume of the bath.

Four little fish we got from the pet shop. Tiny things. Be lucky if they were 2" long. Well now - about three months later I guess - they're four inches long and I begin to wonder..

How long will we be able to keep them in there?

Can their growth be controlled - i.e. do fish put on size where humans put on fat - so that a fish fed less will only grow more slowly and conversely fed more will grow more than is needed for health ?

And we add rainwater from time to time and change water from time to time, along with running 24/7 a filtered pump at 400 litres/hour - and it has water plants in it that have survived happily all this time ( six months, a bit more) but we wonder about fish ponds we've seen/heard of - could it be a fish pond with none of that? No water changing? No filtered pumping?

 

[pbeemer]

that's a little cramped -- the fish will get about 8 inches long -- but carp are ok with small spaces if the water quality is good, so that part should be ok. however, they would really like a much deeper volume of water to avoid temperature extremes. where do you live? is the tub in full sun?

i don't think that a container that small can support 4 grown goldfish without filtering. plants are a very good idea, although carp like to rip them up and eat them if they are soft. a couple of irises in big pots should do ok, and will help with the filtering. throw in some floating plants to help reduce the algae you'll probably be seeing soon; just consider them to be fish food and resign yourself to throwing more in on a regular basis.

the flow rate of the pump is ok on the face of it, but i'm assuming that it's an aquarium filter, and as the goldfish get bigger you'll be cleaning it out all the time.

 

[abrogard]

The tub is in morning sun only. It has shade cloth on top so midday sun is blocked and it is against a shed wall so the afternoon is blocked.

So they will grow to 8 inches and then stop or drastically slow? In what sort of time span?

I'm seeing algae now. If that's what's making the water all green and murky and I guess it is.

Right - filters blocked. I have a little 300 l/hr filter/pump with a tiny sponge filter in it and a tiny carbonl filter - you see them in all the shops here - filters maybe one inch cubes - and it blocks every day.

The bigger pump I had two of. They came without filters and I made my own. Something like 4" plant pots with shop bought carbon at the bottom and shop bought filter wool on top. Pumped the water into them, hanging above the tub.

The improved the water but didn't make it clear.

And they - the filters - got totally blocked with this green slime which I guess was algae. Had to clear them every couple of days.

The last few days the one remaining pump has been working okay - I mean the filter didn't block - so I've assumed that the algae has been mainly cleaned out, filtered out.

While I had them I was doing close on a 1000 litre/hour.

But since yesterday I'm without either of those. Neither will pump. I think tiny tendrils of green have go into the tiny plastic valves in the pumps. I've had one look and tried to fix but haven't been able to do it so far.

So now they're back where they used to be - with just that little thing going.

I'm awaiting more pumps from eBay.

And I'm thinking of putting something big in there. An overhead filter again. Maybe as big as a 10 litre bucket and a much bigger pump. Thinking a bigger pump like the 'dirty water' pond pump I've got that is rated to 2000 litres per hour wouldn't have such delicate valves. That might clean the thing out a bit. That be okay or the water turning around at that rate would not be good for the fish?

How much green in the water is good for the fish? Or is it really good for the fish to be in crystal clear aquarium type water?

Looks a bit unnatural to me but I admit aquariums all over the world are like that and the fish flourish - and I further admit that there's still many places in the world where the natural water is crystal clear, too, even though that's not what we see here.

I have a water plant in there, been there for months, came from the river, I just reefed a handful out and brought it home. It is short on leaves now. Perhaps I should go get another batch with plenty leaves on it?

Could use some advice on feeding, too. Should I open another thread for that?

 

[pbeemer]

where is "here"?

filters don't filter out algae to a great extent, altho algae can happily grow in them. a slowdown in algae growth rate usually means that most of fertilizer in the tank has been consumed. fish poop is a never-ending source, but there is often some extra in any soil or potting medium that may be in the water.

algae can clog the filter medium and have to be removed (or thrown out). what has probably happened is that strands of algae have gotten into the pump impeller or are blocking the intake pipe. clean out the pipe and then disassemble the pump (this is usually pretty easy), and i bet you find a lot of trash wrapped around the impeller. clean that out -- especially any that has gotten between the impeller proper and the stainless steel shaft it spins on -- and you are good to go.

there are a lot of DIY pond filters in the DIY and pond sections. downsize one of them -- your 10 liter bucket with polyester floss would probably be ideal with a good downflow design. you don't really need charcoal -- that's what the plants are for. the theoretical 2000l/hr seems like a little more than you need, but will probably be fine. my only concern would be that it pumps faster than your filter can handle without overflowing; if necessary put a valve (on the OUTPUT side) so you can throttle it down if you need to

generally more plants are better; try some floating plants like anarcharis.

"green water" is pretty much irrelevant for goldfish; they can't eat it, and don't much care one way or the other. aesthetically, you want clear water so you can see them well

goldfish never really stop growing, although the growth rate slows down a lot at 8" the main limiter is probably temperature, since the don't move as much, and can't eat and digest as fast, as the water cools down. never feed them more than they will eat in a few minutes

 

[abrogard]

Currently 'here' is on the Murray, South Australia.

Don't need the charcoal? Is that because it is a growing medium for algae and I've got it growing elsewhere? Or something else?

Didn't I read something about some organisms growing in the aquarium that would change the nitrites into nitrates (or the other way round?) and isn't that what the charcoal ( or carbon granules, they say ) is for?

Or are those 'organisms' actually the algae?

 

[pbeemer]

the biological part of the filter is a bacterial coating on whatever rigid material you have in the filter. (they grow on all wet surfaces inside and outside of the filter as well, but the plastic / ceramic media used in filters provides a LOT of surface area to house a lot of bacteria. )

your fish excrete ammonia into the water in their urine and through their gills. high concentrations of ammonia are bad for the fish because it damages their gills (among other things). some types of bacteria convert the ammonia into nitrites (slightly less bad for the fish than ammonia), while others then convert that nitrite into nitrates, which are much less of a problem to the fish.

the nitrates are a primary fertilizer for algae and larger plants.

while activated carbon can absorb a fair amount of nitrates, you have to change it out for new carbon when it is "full." this gets expensive pretty fast, especially with "high flow through" fish like goldfish. you are better off with plants which will continuously extract the nitrates.

the algae can do this to a certain extent, but you are better off with larger plants which can absorb a lot of nitrates without causing the problems that algae does.

 

[Goodcreature]

You really are only going to be able to keep one goldfish in there. Goldfish are massive poopers, and the reason you have that green water is because the nitrate levels are plenty for the phytoplankton to thrive. If you cut down the source of the nitrates, the fish, it will be much easier to handle the algae. Even then, with the size of the container, you'll have to do water changes every two weeks or so and have plenty of floating plants in there to use up the nitrates. That might be able to get your nitrates down to the levels they should be at, which will in turn control the algae in your pond.

I think the 1000 L/hour is a pretty good rate for the size of the pond you have. Just make sure that you have filter media for the bacteria to grow on. I don't know what you use over there, but common choices here are bio-balls or lava rock, since they provide so much surface area for the bacteria.

 

[abrogard]

Thanks all for the advice. I'm further along the road but still a tad uncertain.

I have one problem or two problems?

I must grow bacteria to turn ammonia into nitrate. That's problem 1.

Then I must get rid of the nitrate because even that's not too good for the fish, right?

By growing algae (how?) to eat the nitrate or putting plants in there that will do it. So that's problem 2.

Or is there a problem 3 that calls for filtering for some other reason?

Or a problem 4 that calls for 'oxygenating' the water?


Amongst other things I get confused by the commercial 'filters' and their sales talk. For they never describe what they are filtering and they frequently have sponge filters in there and carbon filters, too. Which makes it look like they're doing two jobs - or trying to.



I am proposing to put a large filter in there - a 10 litre bucket one third full of polyester floss - and pump water into it from filterless water pumps totalling about 1000 litre/hour capacity. And the water will dribble down through that floss and down into the bathtub below.

And put handfuls of nondescript water weed pulled out from the water's edge of the river in there, too.

And that's it.

Should that work?

 

[pbeemer]

that ought to work, although it takes a bit of time for the bacteria colonies to stabilize. and remember that 8 goldfish is really more than your "tank" has room for. keep the water reasonably high; it is easier to stabilize a larger amount of water. it also gives the fish more room.

an open-cell sponge filter does two things -- it filters out large-to-small particles (depending on the size of the holes in the sponge), in a really easy-to-clean medium, and it provides a lot of surface area for bacteria to colonize as long as it is not filled with crud. you might consider putting a sponge filter in front of your pump to keep most of the crud out of the moving parts and your floss. filter foam enclosing the intake of the pump is cheap

1. the nitrifying bacteria are everywhere in the world; they will grow in your filter if the conditions are right -- wet, lots of oxygen, and ammonia or nitrite to digest. you can speed this up by purchasing bacteria cultures, or better by using old water and filter media from an existing aquarium filter.

make sure the water from the pump sprays out over the whole area of the floss so it is uniformly wet.

2. plants (including algae) then "eat" the nitrate as part of their growth. most of us don't want lots of algae covering the sides of the tank or turning the water green, which is what the other plants are for

i would cover the pail with a lid so you don't have algae growing on the floss, which might junk it up. that would also reduce evaporation losses a lot.

3. partial water changes every so often will keep any trace contaminants from getting out of hand.

4. spraying the water onto your floss should provide plenty of oxygenation for the water

 

[abrogard]

I may put filters around the water intakes. I may not.

These pumps I'm using all seem to be pretty robust in that regard - they have some open impeller system that doesn't easily clog up. What clogs up is the filter around the intake! Both the slots in the plastic cover and the actual filter plastic foam in there.

The latest pair of such pumps I have working in there don't have any filtration on the input and they're happily sucking it up - so maybe they're better without.

Here's some pics of my little setup. Excuse the general untidyness of it all. And not 8 fish at the moment: 4. You can see them all there - rushing to me for a feed.

And you're suggesting I may have to cut them down to a single one. What would I do with the others? Just kill them or can I put them in the river? Or are they 'carp family' and prohibited?

If I want many fish in there - for the kids - then I suppose I need tiny fish. Sticklebacks or something. Small freshwater fish. Do acquaria sell them or should I go try to catch some? And they live okay in home 'ponds' like our bathtub?

You can see here the flowerpot filters I use. A plastic plate on top to distribute the water stream. I'll be making one large one instead of the two small ones.

That junk at the end of the bath is a cover for a hiding place for them and wheel rim for a weight (stop the kids pushing the cover off) and a water pump (hand drill operated) for pumping out water when I want to change the water.

Various unnecessary plastic pipes around the place because of experiment with previous pumps.

You get the idea.