I have a 180 ltr aquarium and added 2 platys after a few weeks and the tank looked like it had cycled after water tests etc. They were fine and after a month I added 4 guppies. all was fine, but after 2 weeks, the algea seemed out of control, and was all over the plastic plants and ornaments I had in the tank. The shop I bought the fish from said the best thing to do was to get a few catfish to eat all the algae. Did that and added 4 catfish afew days ago. One of my platys is stressed now and is either hiding under the ornaments at the bottom or floating at the top near the heater. I have done a couple of 10% WATER CHANGES and added some Aquasafe, as my ammonia levels were up to .50, but he is still not eating and not himself after 4 days. Any ideas?? It is flapping a bit and making erratic movements.

Take the catfish back and demand a full refund, the shop should not be selling you fish to control algae. By adding more fish, you are in effect adding more food for the algae.

What species of catfish did you buy (a photo would help)? Bear in mind that several species of catfish that are commonly sold for 'algae control' (including Plecs) can grow very large and very few actually consume algae as the main part of their diets. For example, the majority of Plecs are omnivorous and many die due to not been provided with enough dietary protein.

I wouldn't add anymore fish for now and allow the tank to settle down. The best way to control algae is to use live plants. Fast-growing stem species such as Hygrophila will out-compete the algae for excess nutrients such as nitrate and phosphate under the ideal conditions.

It's also important that light, CO2 and nutrients are all kept in balance; and ensure that the tank is not exposed to natural sunlight. All too often have I seen fishkeepers overlook even the smallest of things whilst attempting to control algal growth. Light, CO2 and nutrients are all so-called 'limiting factors' of photosynthesis. If one of these 'limiting factors' is deficient to the point where the level is detrimental to plant growth, algae will simply re-take control of the aquarium.

Any artificial lighting over the tank should be plugged into a timer and the photoperiod set to no more than seven hours a day.

Just one last thing. When you carry out water changes, check the nitrate and phosphate reading of the water you are using to re-fill the tank. Very few areas of the UK have tapwater that is of particularly high quality, and if the water is laden with excess nutrients, you are in effect feeding the algae whenever you carry out a water change.

Thanks for your reply.Lots of questions coming up.
I feel so inadequate now as I know so little and I trusted the Aquarium shop advice.I don't even want the cat fish. They are so ugly. He gave me 2 plecs and 2 smaller ones. The plecs are hiding most of the time. He told me to return the catfish when they grow too big, but I would rather take the plecs back now as they give me the creeps.They are so ugly. I don't know how to get them out of the tank as it is a corner tank and very deep and the plecs are hiding. How am I going to get them out? Are you saying they have caused the ammonia level to rise? My platy was fine before they went into the tank. My room has a lot of natural light and when it is sunny I have to keep the blinds closed, and I don't usually put the lights on in the tank unless it is a dull day and if not only after 4pm untill about 8pm. What is meant by the co2 level? How do I keep it right? What do you think is wrong with my platy? He does not look diseased, but looks lethargic and either hiding or floating near the heater at the top. He is not eating. I have not fed them these last 2 days. Can you answer any or all of these questions for me PLEEZ ?

I would take the fish back now, don't take the store's word for it when the owner says they will take the fish back. You could end up going back there in a few months and the store could back-track, potentially leaving you stuck with two large Plecs which are very difficult to rehome.

A sudden and large increase in biological load can cause the ammonia level to spike. However, a reading of 0.5ppm shouldn't do too much damage, and test kits can easily give false readings. To be honest, the ammonia isn't really something to be concerned about; a few water changes and minimal feeding should keep it down.

Plants require CO2 (Carbon dioxide) for photosynthesis. CO2 can be dissolved in water and it can very easily diffuse from the atmosphere into water, however the concentration of CO2 in the air is simply too small to satisfy the demands of live plants. A lack of CO2 and no live plants is simply a recipe for algae growth.

Carbon dioxide can be dosed in several forms, however the required concentration depends on the intensity of your lighting. The more intense the light is, the faster plants and algae photosynthesize, thus consuming more CO2.

Pressurized systems are ideal for large tanks from an economical point of view, however they are expensive and can be dangerous if used incorrectly. Yeast-based systems and Liquid Carbon additives are also available, both of which are cheaper and ideal for smaller, moderately planted aquariums.

Carbon dioxide is normally measured using a drop checker. This is simply a device which is filled approximately half-full with aquarium water and a test reagent added. The colour of the water after the test reagent tells you the concentration of CO2 within the aquarium water. If the water in the drop checker is green, the CO2 level is correct. If the water is yellow, the CO2 level is too high and if the water has turned blue, the CO2 level is too low.
The amount of CO2 added to the water can then be adjusted accordingly.

There's no need to start using CO2 yet, not until you have at least purchased some live plants to help combat the algae. For a 180 litre tank, the Liquid Carbon would be ideal for most hardy plant species such as Hygrophila and Cryptocorynes.

As for removing the Plecs, wait until dark to find them, as catfish are primarily nocturnal. You could invest in a fish trap, however two nets and a bit of cunning would be a quicker way of doing things. Bend the handles of the nets into two right-angles so you can get the nets into the corners of the aquarium.

Remember, that fish can suffer from internal diseases which don't always show external symptoms. My own guess is that the Platy is suffering from the effects of ammonia poisoning. Ammonia levels can rise and fall over the period of a few hours, as biological filtration catches up and breaks it down into nitrite. The best thing to do is to keep a close eye on the fish for now, however report back if anything changes.

use a bottle of cycle and turn off ya light for a few days. simple and as stright forward as can be let ya filter mature the bottle of cycle should help this and kill the light to kill the algae best off luck

What does that mean ( a bottle of cycle)?

I decided to try to catch the big plec this morning as I thought leaving him outside the tank all night in a bowl after catching him might kill him by the time I got him to the shop next day. This morning I had to remove every ornament form the tank until I found the big plec and it was really difficult to catch it. I did eventually and headed into the aquarium shop to return it. I then added the ornaments again and added some aquasafe to the water after doing another 4 gallon water change. The fish shop told me I had made it worse by doing the water changes as my tank is still cycling being only 11 weeks old, and it would now take longer to cycle. I have left the 2 small catfish in the tank with the tiny other plec. I have four guppies also and 2 platys - one of which is still poorly. I was advised at the shop to flush it down the toilet if it does not recover ( I won't be doing that anyway.) I was told that there is a new additive being stocked soon which removes all algae. I was told that plants will not make any difference and not to add anything more to the tank just now until it all settles down again. Honestly this is all becoming more and more confusing and I am beginning to wish I had not bothered with the aquarium at all.
This is the most stressful hobby I have ever been involved in.
What do you think of the remarks by the shop?

on what they say about plants: the science is very much against them. its the basic nitrogen cycle. fish produce nitrite, which is "eaten" by bacteria in the filter, and excreted as nitrate. this nitrate is what feeds the algae. so the more fish, the more nitrate. nitate is basically fertilier (its what farmers put onto their lad to increase crops), and aquarium plants are no exeption. put plants in, and they will "eat" the nitrate, basically removing the algaes food. more plants = less algae. very simple. as for chemicals that claim to remove it, nevertust them! most kill all plants, even ones you want, and are suspect for use with fish i many cases. best to avoid them. the only other real way of rediucing algae is to limit light. an aquaium should only be lit between 6 and 8 hours a day. in fact, the light only exists so you can see the fish, and they fish are quite happy to live with no light. so really, it only need be on when your looking at them. so technically, you could have it on when you get home from work, till when you go to bed. thats all you need. would save electricity too.

Well, thanks you so much everyone for your advice. My platy is feeling a bit better this morning. When I went to them first thing this morning, he was at the front of the tank and swimming around with the other one. That has not happened since Sunday. I put in a pinch of food and he actually looked like he was interested. There is a great improvement today, and I am hoping it will continue. It seems common sense to me to do a few small water changes to improve the ammonia levels, but the shop told me I had now gone back the way, and it would take longer for my tank to do it's full cycle. Anyway I would rather have that than dead fish.
I usually just feed the usual run of the mill fish food, but what does everyone think of the food called Nutrafin Max. I was having a look at it and it has bits of dried worms etc? I would not be changing anything just now, especially the food, until things settle down again but wonder what the opinion is on this food.

what they say about it taking longer now is true. the bacteria uses the ammonia in the water as food, and obviously the more there is, the faster it will grow. however, with ammonia being deadly to fish, you currently dont want high levels, as it will kill them. tis is why we always reccomend cycling the tank using bottles of ammonia before adding the fish. its quicker, and less dangerous.
so yeah, the tank will cycle slower with you doing the water changes, and if you want it to cycle faster then you can stop doing them. however, without doing them, you would probably kill your fish in there.

some shops really annoy me in the advice they give >.<