Object lessons

An article by Andreas I. Iliopoulos

Many things have been written about how an aquarium should be. Many more things are also being written about the same issue and lot of information is coming and going.

Well, this time, I have chosen to write about how one should NOT set up a tank. Along with that list, I have also included a short MCH relevant articles guide to avoid such mistakes.

26 rules of thumb

  Do NOT buy or build a tank before you decide what species you are going to keep in it.

 Do NOT house very large species in very small tanks.

 Do NOT obtain any aquatic organisms without knowing about their biology and specific needs first.

 Do NOT use a small filtering unit to support a large aquarium.

 Do NOT neglect checking your tap water parameters before using it in your system.

 Do NOT use substrata and “decorative” items that make your fish tank look like your favorite dance club.

 Do NOT neglect to act out the needed routines for the maintenance of your system.

 Do NOT neglect a fixed schedule to run a series of tests on the physicochemical water parameters of your system.

 Do NOT neglect to carefully observe both the fish and functioning of the equipment in your tank on a daily basis.

 Do NOT house incompatible species together.

 Do NOT overfeed or intend to feed with improper foods.

 Do NOT buy hybrids and artificially man made ornamental strains of aquatic animals.

 Do NOT buy organisms that are recorded as poor survivors in captive conditions.

 Do NOT neglect proper maintenance and storage of your electronic tests’ devices.

 Do NOT neglect the proper storage of foods.

 Do NOT ever feed foods from mammalian products or byproducts and Tubifex.

 Do NOT knock on the glass of a tank, or let others do so.

 Do NOT expose your tank and its inhabitants to sudden and intense visual or loud audio irritants.

 Do NOT trust all the petshop owners.

 Do NOT buy goods if you are not absolutely convinced that they are essential for the good and healthy functioning of your system.

 Do NOT use any medication if you are not sure that there is a health problem.

 Do NOT use any drug if you do not have good knowledge about its operation and the needed precautions that one should take when using it.

 Do NOT introduce captive organisms to natural biotopes.

 Do NOT hesitate to search for reliable (formal or electronic) sources of information and to ask advanced aquarists, hobbyists and fish-keepers, even if you believe that what you are asking is despairingly stupid.

 Do NOT run a display tank without supporting a quarantine one.

 Do NOT get disappointed.

Given here are some examples of the actions one should never follow. For most of them, I was an eyewitness. Although I have given a lambent style in these facts, I can ensure you that it wasn’t pleasant at all. So here we go:

 1. Some days ago, I was asked to go and check a “sticky” aquarium at one aquarist’s house. There, I saw a tank measuring (Length x Width x Height) 40 cm x 27 cm x 37 cm, with a total volume of less than forty liters (40 l) of water. This tank houses two (2) semi-adult long-finned Pterophyllum scalare scalare, with a body diameter of about eight centimeters (8 cm) each, four (4) fully grown Poecilia latipinna, about ten (10) adult P. reticulata, a pair (1♂ + 1♀) of adult Xiphophorus helleri, four (4) Corydoras paleatus and one (1) Hypostomus plecostomus, measuring about twelve centimeters (12 cm) in length.

The system was supported by a small internal canister filter, a twenty-five Watts (25 W) thermostat and one (1) Arcadia – Original Tropical fluorescent tube with an output of eight Watts (8 W).



Pic 1 & 2. These two photos show two semi-adult P. s. scalare specimens that hardly fit in this small tank. The small internal filter that supports this system is on the left side.

The question that the owner asked me was: ”Why do I have casualties? P. s. scalare are killing their other tankmates.”


  2. A year ago I entered a shop that trades electronic goods and I faced an aquarium measuring eighty centimeters of length and relevant for the rest of its dimensions. I average it to have a volume of about seventy liters (70 l). This tank has two (2) fifty centimeters (50 cm) long Pangasius sanitwongsei specimens, facing the backside of the tank, hustling and stressing each other to gain a better position, thus to get away from the curious customers.

I was extremely sorry for these two poor fellows and I asked the manager: “Why are you keeping these large animals in such a small enclosure?” His answer was: “They weren’t so big at first. They became large in this tank, but they are doing fine, as you may noticed”. I was petrified by this ignorant answer, and I left the shop without buying the mouse pad and the inks that I was about to buy. What I can suggest on this matter is to take a look at the following article before doing anything:


  3. One friend telephoned me saying that it was really urgent to pay him a visit and to take a look at a pair of fishes he had bought and that they probably are the ones that have devoured all his Paracheirodon herbertaxelrodi within two days. I asked him what is the species of these new specimens and he said that he had no idea. So, I went to his house and I saw two very beautiful, almost fully grown (about eight to nine centimeters each), but completely full Epiplatys sexfasciatus that were calling urgently for club sodas to digest the smaller, slower and innocent cardinals.

  4. I couldn’t believe my very eyes when looking at a two hundred fifty liters (250 l) tank, supported by a tiny nearly clogged internal canister filter with a capacity of one hundred twenty liters per hour (120 l/h). This time, the question was: “Why the water is so green, the bottom is so muddy and most of my fishes dying within a week?” For further reading you may use the URL given below:




  5. A guy was coming to my lfs every day for nearly a week, and all he was buying was pH-Down, the product of Aquarium Pharmaceuticals that is used to lower the pH. Once, I asked him: “What are you doing all this acidic stuff?” He told me that he was trying to lower the pH value in his tank, but unsuccessfully.

The water he was using was so hard that had the buffering capacity to increase, within twenty-four hours, the pH in his system, no matter how much of the product he had used to decrease it.

A woman had both a permanent casualties problem and aggressive algal blooms, although she was performing partial water changes weekly. She was using water from an underground rainwater reservoir. I went to her place, and I saw that one level above the underground reservoir was located a vast green house. Obviously, the landlord of this property was using fertilizers that were – by capillarity – driven into the lady’s reservoir. So I ran phosphates and nitrates tests.

I found Phosphates: > 5,0 ppm and Nitrates: > 150 ppm.

  6. Although a friend who was a newcomer to the hobby asked me in January 2003 how he should set up his Malawi community tank, when I was invited to his place to see the result, I found just two medium to small stones in the tank and a cobalt blue colored gravel. He asked me my opinion, and I asked him if he wants the truth. He said “yes” and I told him: “It looks like a very fancy disco!” He was disappointed a bit, but he said he liked this lay out a lot. I repeated to him the reasons why cichlids should be in tanks with natural sand, which is to prevent the male animals from stress due to their struggle to produce more color than the colorful surroundings, and noticed again that most of the Malawians are blue.

The next September he called me again to take a look at a new aquarium he installed in his fast food. I found a large piece of bogwood that a petshop owner sold him as a perfect decorative item and colorful gravel as well. This time, it wasn’t only cobalt blue, but fluorescent pink, yellow and green grains enhanced it as well.



Pic 3 & 4These are the “perfect” substrata for Malawi cichlids, for this aquarist, and obviously the lfs owner who agreed and sold him these “disco” gravels.


Pic 5. And this is the way to create the appropriate landscape for Malawians.  

One shall find detailed information about proper aquascaping in the following articles:











  7. “Help me, I am desperate. I’m losing my fish at a galloping rate for the last two days, and I don’t know what to do.” I found high concentrations of nitrites in her water when I ran my tests. She told me that four (4) months ago she saw that the fishes were doing fine, and so she thought to stop performing partial water changes, considering them useless. On the other hand, she managed to introduce about twenty (20) more specimens in the tank. The filter was completely clogged. I got it out to clean it. I was surprised it wasn’t burnt yet. It was hot as hell. If you would like to answer some more of your questions on partial water changes, you may use these articles:




  8. Although an advanced aquarist, he did not run tests for about six (6) months or so. One day he found all his stock dead. I measured the KH and it was ≤1° dKH, Ammonia (NH3/NH+4) ≥ 5,0 ppm and Nitrites (NO-2) = 2,0 ppm. A strange daily loss of carbonates pushed ammonia slowly but steadily to its peak within four (4) days. Nitrites were also high. The problem disappeared after the peak was reached.

Pity! He could have saved all his fish quite easily if he managed to run tests regularly.

  9. One of my customers lost most of his fish due to the simplest and easiest parasitic pathogen to confront, and that one can encounter in a fresh water tank.


 Pic 6. The symptoms of Ich are rather obvious. Photo by Chris Andrews (Ichthyopathology ph.D)

Ichthyophthirius multifilliis (Ich) can be successfully treated if detected in its early stages, especially if the infected fish are scaleless as this customer’s Botia macracanthus. Obviously, this aquarist never paid the proportional attention to his system. The newly introduced B. macracanthus stressed from their new environment and brought forward the parasite. Afterwards, the aquarist kept on not observing his tank and the pathogen multiplied in vast numbers and infected severely not only the B. macracanthus but the rest of his fish as well. The result was two (2) B. macracanthus, nine (9) Rasbora pauciperflorata, six (6) Corydoras aeneus and one (1) Ancistrus dolichopterus dead. The treatment had to be repeated three consecutive times, instead of one to save the rest. The further results were the loss of the biological stock, and the toxic compounds being raised to their peak points. So, more dead fishes. These two articles bear out the importance of personal observations:




10. One petshop owner that I know asserts that rift lakes’ cichlids are the worst choice for a community tank. The reason for this statement is their aggression. He told me that he had never had success with such a system. Some of the tankmates would always kill or harassed to death all the others.

It is quite apparent that he hadn’t paid any attention to the species he was housing together.

One young woman once complained to me that she couldn’t introduce any fishes in her tank because the two Astronotus ocellatus she has were permanently killing everything. This “everything” was several CHARACIDAE species and Colisa lalia. Aggression is a natural phenomenon with territorial species, but there are many ways to be avoided. Many of these ways are described in these articles:





11. A friend and colleague had to deal with severe losses of all of his Tropheus species and Eretmodus cyanostictus that were housed in his display tank. Along with the above-mentioned species were also housed Neolamprologus brichardi, N. leleupi longior, N. tretocephalus, Altolamprologus calvus and A. compressiceps, as well as Ophthalmotilapia species. He gave all the species the same food to this tank ( how could he give different foods that would be accepted from the different species?). The result was that Tropheus disease came and swept away all his herbivores. See the relevant articles on this issue: http://www.malawicichlidhomepage.com/aquainfo/fish_compatibility_1.html




12. I do not have to do any comment on this, as MCH authors have already written and published very detailed articles on this issue. You may see all this information on:



13. This topic is relevant mostly with marine animals. Many fishes from the families CHAETODONTIDAE, POMACANTIDAE and some from the LABRIDAE, CARCHARINIDAE and SERRANIDAE families are poor (to very, very poor) survivors in captivity. This is the main reason for the losses of this kind of fishes in our marine aquaria. Learn which are the poor survivors and which are the ones that are adapted well to captivity before you buy. Also, boycott by any means the imports of the poor survivors. A good source for this information is the new book of Robert (Bob) Fenner with the title: “The Conscientious Marine Aquarist”.


14. Many advanced aquarists, hobbyists and fishkeepers have obtained electronic pH, Redox and relevant gauges for more reliable checking of their water parameters in their tanks. This is fine, but one should take a good care of these specialized instruments, or false readings will occur. I’ve seen quite a lot damaged probes, totally useless to the user. A good source for the importance of these devices and their servicing is the article on the URL:


15. The worst enemies of dried and freeze dried fish foods are moisture and light. The worst enemy of frozen foods is high temperature. Have in mind that dried and freeze dried fish foods should never be handled with wet hands. If the cans that one buys are of an economic size, it is essential to keep them in the refrigerator after opening. The frozen foods must be kept at  -17° C permanently, so do not buy large quantities of them, because you cannot keep them fresh in an average freezer, for long periods.

16. This one is clear enough, I suppose. Although I shall mention that fishes cannot digest mammalian fats as their organisms never had contacts with terrestrial mammals and their flesh or fatty acids, so if one feeds them this stuff, it increases the possibilities for alimentary diseases and, of course, deaths. Regarding Tubifex, I have nothing further to say. Many aquarists, hobbyists, fishkeepers, researchers and publishers have already said enough.

17. Sound travels inside water about forty (40) times faster than it travels in the air. This means that when knocking the glass of a tank, the guest organisms apprehend sound much more strongly than we do. This may cause stress and diseases of the livestock.

18. This also brings out stress in aquatic organisms that, until this time, were in darkness and silent. In the following article, you shall find a very good method to give your fishes the time to adapt in day light conditions:


19. Petshop owners are merchants that must earn money to sustain their financial investments and to pay bills and taxes. Most of them are just dealers and not hobbyists or aquarists. Some are not honest, either. You may trust your dealers or your lfs owners as long as you have already ascertained their honesty and their knowledge. If they trade well-known products and can give basic, but reliable info about these products and the livestock they sell, then you have some reasons to start trusting them.


 Pic 8. Please find me a better reason – if not profit – why the lfs owner sold this “thing” to an aquarist who desired to house Malawi cichlids into his system.

It is also essential that an lfs owner will sell you or “force” you to buy things that MUST be used in a tank, and accordingly, will discourage you to buy useless, dangerous or ugly items and materials, as well as incompatible aquatic species.

20. Save your money and buy what you really need and not what someone suggests only for the sale and increase the turn of the shop. Ask exactly what the product does. Read the manuals, and ask more questions. Search among other aquarists for the specific product before you buy it. It is not going to be lost from the shelf next week, or you could order it if it is sold out.

Also, do not go and buy a fish before you read about it first.

Do not forget. A salesman would like to earn money, but you want to have a viable aquarium.

21. All you want to know about fish diseases are in these pages. Study them now and study them any time you believe you have a particular problem in your tank:








22. Drugs are not toys to play with. They could kill your fish or cause health problems (poisoning, allergies, etc) to yourself, as well. Many of them are very dangerous if swallowed or contacted with your skin, mucus and eyes. Antibiotics, for instance, are very dangerous to be released in natural biotopes. All in all, drugs should be used according their manufacturers and with taken all the prescribed precaution to be successful, functional and safe to you and to the environment. Get yourself prepared for extreme acts such as euthanasia, if an individual from your livestock has something that it is not reversionary. Study these articles before you start playing the veterinarian:





23. This is not difficult to be understood. Introducing animals from foreign biotopes into our natural biotopes can cause a domino effect on all the flora and fauna of a stable environment. Imagine that the introduced animals, fungi or plants may have not any natural enemy to control their population in environments alien to their own. Think that they may be vectors or media of transporting unknown pathogens. Imagine that they may are predators or competitive to other life forms that occur in a biotope. In such a case, the only thing you shall achieve, if you are careless, is a dangerous imbalance with incontrollable consequences.

24. Many friends have come and complained that when they introduced a new fish into a tank, the diseases mysteriously followed. It is not any mystery, here. A new fish may be pathogen’s’ carrier or even sick due to the fact it is newly imported. Unfortunately, not all the diseases exhibit obvious symptoms, so it is not wise to buy a fish and then introduce it straight in your display tank. A small hospital tank running in your house may save you from spending money, treating a massive main tank, or loosing your precious animals and your courage to go on the hobby. A nice addition is the info that is included in the next mentioned URL:


25. Asking has never caused evil effects. Even stupid questions – sometimes – could be very valuable, so ask, ask, and ask. The only thing that one should take into account when asking is who is answering. Be careful selecting the ones you are asking and you are not going to lose.

26. Never do that favor to the weak part of yourself. The knowledge about fishkeeping that is available nowadays was gained due to optimistic and hard working people that maybe were disappointed for a moment, but the very next moment were again in action. Do not forget that.

Text and Photos: Andreas I. Iliopoulos/MCH

Many thanks to Carli Debusk for her Editorial help.

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