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Here are our considered answers to your problem enquiries.

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Please can you help me? Last year we bought a house which has a small pond in the garden.

There is a fountain which works when switched on from the house. This works. Is it good for the fish apart from being decorative?

There appears to be provision for a small waterfall coming from a pipe in a mound of rocks. This does not work. Behind the mound of rocks is a box which I presumed was some kind of pump. I took off the lid and see it is full of wet mud with a pipe visible at the top. Is this a pump or a filter and should I remove all the mud. I cannot see how the electricity is connected to either the fountain or the filter/pump box.

Also I noticed that one of the small fish kept wriggling onto the top of the pond weed which is quite thick at one end of the pond. I thought it was stuck but when I came near it just wriggled underneath again into the water. I have cleared some of the pond weed (there are two lily plants and some kind of water iris as well so it is quite well established) but wonder what the fish was doing - need I worry?

I know nothing about fish and have just fed them except for the very cold weather and put in a water heater in the winter in freezing weather so it did not freeze over as it is not very deep (scarcely 18inches). I hope to renovate the pond in the Spring but do not want the fish to suffer in the meantime.Thank you, Lesley

The fountain, apart from looking decorative, can be beneficial to the fish, especially during hot weather as it helps to aerate the water and maintain oxygen levels. The only time you might want to turn it off is during windy weather when the spray might not all fall back into the pond, and so the pond would lose water.

The box in the rockery sounds very much like a filter, especially as it is full of mud! It may well be that the fountain has a 'T' piece connector in it (in the vertical pipe just under the jet) which allows water to be pumped up to the filter box. Here, the water would trickle through probably some form of sponge material to strain out the dirt from the water and then the water returns to the pond via the pipe you see sticking out of the box.

There must be an inlet pipe to the filter box – it might also have a tap or valve on it to switch the filter off for maintenance purposes. It might not have been turned on again last Spring?

Certainly there would be no harm in cleaning out the mud, if only to see what's underneath! If the sponge filters have not disintegrated to any degree, they may be put back into the filter for re-use.

Without going into too many technicalities, after a filter has been cleaned it will take a few weeks to return to its full efficiency again. Subsequently, when you wash out the filter medium, you should do so using some water taken from the pond so as not to totally destroy any beneficial cleaning bacteria that the filter sponge has living in it. For this first clean-up, don't worry too much about using pond water, as there is no water coming out of the filter it is obviously not working at the moment and so there won't be too many bacteria to destroy.

Turning to your fish, I think that it probably wriggled up on to the water plants during the excitement of spawning, and being chassed by a male fish. Alternatively, and you did say it was a small fish, it may have been chasing some surface dwelling insect and just overdid things a bit.

As far as caring for your fish, I think you're doing all the right things (even if you don't realise it at the time). Don't feed the fish at all once water temperatures remain consistently below 10 degrees Centigrade. They will not need feeding and any food left uneaten in the pond will pollute the water to sore up algae problems next year and if the fish do take in food they can't digest it at these low temperatures and this again leads to health problems later on.

It might be a good idea to get some of the silt (if any) out of the pond this autumn rather than leave things until next Spring. Cut back all the dead water plants too, as any decomposing matter in the pond also can cause trouble next year.

You may find our Pond Care Sheets on our website useful.



I've been keeping fish for nearly a year now in quite a small tank (30x30cm), 25 litres.
It has an undergravel filter with an air pump. In it I have 2 young, small Lemon Goldfish.

I recently went on holiday for four weeks, at which time I had just the one fish.
As I was away for so long, I used a holiday block, but on arrival home my fish was gravely thin and on the bottom of the tank. Fortunately, she recovered and was once more active. Later, I introduced my other fish.

The two do not get on well. The new fish frequently bites the old and she consequently gets very little food. Now, although not thin, she sits on the bottom of the tank again a lot of the time but does not have swimbladder or parasite problems.

The water quality is tested ok and I always carry out weekly water changes. They are fed a varied diet, I am not overfeeding, and I am within the limits of fish for my little tank Strangly enough, the other fish is active and healthy. Is something wrong, or is this normal behaviour? Please help; I don't want her to die!!! David

Your tank is indeed on the small side, even for only two small Goldfish, however the cause of the problem is probably more to do with the use of the holiday block for the period that you were on holiday.

With the use of an undergravel filter it is likely that some kind of toxic material may have developed in the gravel too. It may be that the concentrated 'food' in the tank caused some kind of ammonia/nitrite/nitrate build up to which your fish reacted.

Even with a small tank, a regular partial water change is beneficial but you should not change too much at once – 10% would be the maximum, to ensure that the bacterial life in the undergravel filter system is not set back at each water change. You could try extending the water change period to three weeks and see what happens.

Fish biting each other is fairly common in Goldfish although what may have been happening is that the fish was being head-butted rather than bitten. This occurs when a male decides it's time for a little spawning activity. I quote from a previous reply given by Bob Esson on our website:

“Regarding the other fish “biting its bum”. It is not biting it, Goldfish teeth are at the back of the mouth, they are not biting teeth; they are called pharyngeal teeth and are used for grinding and crushing food.

What it is trying to do is to start a chase as a prelude to the breeding pattern. You may have a male and female. Has the fish that is doing the nudging small white tubercles on its gill covers (operculums) and/or on the first ray of its pectoral fins (these are the fins just below and slightly to the rear of the gill cover)? If so it is a male; if the other fish has none, it could be a female.“

Your fish would be better off in a 24” (600mm) long tank, especially during periods of hot weather where the water conditions are less likely to fluctuate so much.


I have recently purchased some live rock and was hoping you could tell me what to feed them. The more information you can give me the better. Julie

The real answer is that you do not have to feed living rock, but you may be confused by this statement.

Living rock is used in the marine aquarium to help maintain water quality. It does this by means of bacteria which live both on the rock's outside surfaces and in all its internal structure.

Basically, the 'outside' bacteria deals with any ammonia-based organic material not already removed by the protein skimmer converting them to harmless nitrate, than the 'internal' bacteria get to work on the nitrate to convert that back to nitrogen.

What you may be concerned about is the welfare of the tiny animals that you will discover growing on the outside of the rock. These will eat the same food that you feed invertebrates such as soft corals, tubeworms etc with.

You can get inveretbrate food at your aquatic store. It is usually in liquid food and you just mix the stated dose up in some aquarium water before adding it to the tank. You might consider turning off the tank's filters for a few minutes during feeding so that the filter doesn't remove the food from the water before it gets to the invertebrates on the rock.

One thing you should ensure is that yopur aquarium has a good water circulation within it that reaches all parts of the tank. This will bring food to every tiny animal living on the living rock.


I have twelve goldfish in my garden pond and they seem to be fine. They eat well, around 4 times per day of fish flakes. My worry is not with the fish but the water.

It appears clear to the eye but all parts of the rockery and ornaments that come in contact with the water are turning green/dark brown. Is this alright or do I need to add any solution to the water? The pond has a water feature and this operates 24 hrs providing moving water. Many thanks if you can help me out. Charlie.

It is quite natural for areas of the rockery nearest to the water to turn green and/or brown. Under the influence of the moisture - or from splashes from the water feature - many small algae and mosses are likely to take hold. As some of these die off (we had a frost recently!) these will turn brown. Even if some of these 'plants' actually come into contact with the water they will do no harm.

Incidentally, as water temperatures fall, you might need to cut down on your 4 times a day feeding routine. Fish will not need quite as much food, they become lathargic at lower water temperatures and any food they have taken in may lay in their intestines undigested and cause problems. Changing to a more easily digestable wheatgerm-based food around now is often recommended (and using it again in early Spring).

Always stop feeding completely once water temperatures remain below 10 degrees C consistently.

I think your pond is quite OK and needs no treatment, apart from perhaps clearing out any dead/dying aquatic plants and removing accumulated silt from the bottom, before winter sets in.


Last updated Auguust 31st, 2005