A 700 liter, Paretroplus maculatus species tank

by George J. Reclos

Well, this is how my new tank looks like, just after adding the ten Paretroplus maculatus in it. There is one more to come, whenever we manage to find it - its net-escaping techniques really impressed us. The decoration of the tank is the classic sand / bogwood / stone approach while no plants were added since the system is filter through two overflow devices and dead leaves can prove very dangerous (blocking the inlets). Every new tank is supposed to be better built, more functional and better (or at least more suitably) aquascaped than your previous one - this is what experience means after all. In this tank (originally planned to be a Mediterranean marine tank) there were some things we tried for the very first time. The first, is the use of the sump. The second is the complete elimination of any kind of technical stuff from the main tank. Third comes the high (for a freshwater tank) water flow. Initially scheduled for 13.500 l/h we reduced it to 10.000 l/h which guarantees river like conditions and a high saturation of the water with air, without using air pumps. The fourth new element was a Spartan decoration which was supposed to be aesthetically appealing while at the same time serving the needs of the inhabitants. Finally, this tank took almost 7 months to be completed, which is a new record by itself. It proved to me (and others around me) that I can wait for more than one day with an empty tank in hand. In the end, the growth rate of my Pe maculatus (formerly leaving in an 140 liter tank) forced me to make it operational now.

The whole project was discussed with some friends (Andreas Iliopoulos, Andreas Kamarinos and Minos Pagonis) and we finally decided how this tank should be built. Below you will see the steps that led to the final result.

First comes the galvanized metal stand which has no "feet" but stands on its whole surface. The stand is also longer than the tank for two reasons: a) spread the weight to a larger surface and b) allow the overflow tubes to enter the sump vertically, without bending them. As you can see in the picture above, all electric sockets were put in place before the tank's arrival, a standard procedure which has saved me a lot of time and trouble in the past. The usual rule is make a calculation of the number of outlets you may need and then just double it. At the bottom of the stand we placed more than 300 self adhesive foam pads (the kind you use for the feet of chairs to avoid scratching wooden floors) to allow for any floor irregularities. This also allowed us to move the tank even when filled with water to one third. The metal construction has a 4 x 4 cm cross-section and was painted white by Johnny (who also painted half his mother's plants in a shinning white).

The tank arrived and put in place. You can see me, Andreas and Mr. Antonakakis (the tank builder). Carrying a tank this size is always the most stressing step.

We had the pleasure of meeting Ibrahim Chalili - a marine fish keeper and a very good person with whom we shared our thoughts. His comments were invaluable. Actually, he gave us some good points to consider about the tank and we gave him some Labidochromis caeruleus and Cynotilapia afra "mbamba" for his brand new tank.

There were three holes pre-drilled at the bottom of the tank. The first was an inlet (for draining the tank / faster water changes), the second was an inlet for the 6500 liter tank and the third was not to be used anymore (initially, the tank was scheduled to have three water pumps installed). The innovation of the tank (in its marine version) was that apart from the 10.000 liters of water per hour coming horizontally in it from the side, another 3500 liters per hour would come vertically from the bottom so there would be no "dead" spots in the tank.

The overflow devices in place. You can also see the two outlets. The one in the center of the glass is for the 6500 l/h pump (inlet at the bottom of the tank) while the one at the top right corner is the return of the pump in the sump (3500 l/h).

The same as seen from the outer side of the tank. The overflow outlet you see is the one who set us back almost a week since it was leaking without any apparent reason. In the end we concluded that perhaps it was the over tightening that caused it.

Andreas working with the various connections. I must confess that I admired the quality of his work and the deep knowledge in setting up tanks. I learned quite a few things during this process.

The background had to be put in place before the water since it wouldn't be possible to move the tank afterwards. It took us quite some time to make the necessary holes in it - at the correct place. Despite our calculations and drawings some minor adjustments had to be made in situ.

After filling the tank with water we noticed that one of the overflow devices was leaking. Since Minos is an expert in overflow stuff he came in for rescue. After some trials he finally made it. Nobody really understood why the leak stopped but as we all said "if it doesn't break don't fix it".

The tank is filled with water for the last time - hope dies last. Actually we had to empty and re-fill it a couple of times more.

This is the last time we filled it. Although you can see me a bit pessimistic, everything was OK this time.

The filter material. Sumps have many advantages and one disadvantage. They need a lot of filter material. All this stuff easily made it in the sump.

The classic combination in all my large tanks. Titanium heaters and a separate thermo regulator, all by Schego.

A photo of the space under the tank. Notes: [1] overflow outlets; the short glass which keeps their ends in place ensures maximum air / water contact. [2] water outlet leading to water pump [15] (6500 l/h), [3] water outlet leading to drainage tube [16]; [4] thick floss for large particles; [5] ten liters of Eheim Substrat; [6] seven liters of Ehfi fix; [7] five liters of Ehfi Mech; [8] undergravel plates; [9] small compartment with the sensors of the wireless thermometer and the temperature regulator of the heaters; [10] titanium heaters; [11] water pump (1200 l/h) forcing water through the chiller [14] and the Eco aqualizer [15]; [12] water pump (Ocean Runner 3500) returning the water from the sump to the tank; [13] Ocean runner 6500 for maximum water flow; [16] drainage tube. In addition, the main external unit of the previous tank was used, taking water from the first compartment and returning it in the last one. The bacterial colony in this filter was able to take the load of the fish in the main tank on its own, thus giving time to the new filter to mature. In this temporary situation you must be very careful when you stop the pump in the sump because, due to the three-level construction, the external filter will overflow the last compartment if left working alone. I learned it the hard way - as usually !

The key decoration element in the tank is bogwood. Three large pieces weighting more than 45 Kg dominate the center of it. Two of them - with very beautiful shapes and lots of "crevices" - were donated by Takis Nikiforou, to whom special thanks. The main formation is placed in the first third of the tank's width to create a 10 cm "corridor" in the back of the tank which should be used by the fish for retreat. The disadvantage when working with bogwood this size is that you can't boil or clean it as you would with smaller pieces.  Thus, we only cleaned it with running tap water to remove as many debris as possible and let it in the tank for a couple of days - without fish. After the water became cloudy, we made a complete water change, waited for the water to reach the right temperature, added the right amount of water conditioner, waited for two more hours and then added the fish. Although fish don't like new environments, netting and transportation, the Paretroplus maculatus reacted much better than anticipated in this process. A couple of hours after, they were all happily swimming together. Their schooling behavior is much more evident in this tank. In the small tank they lived some of them remained hidden all day long while some aggression was also noticed. In the new tank, they just swim together. It is funny to watch a lonely fish which spent more time at a particular spot of the tank to rush to the rest of the group. It should be noted that the amount of brown color released by this amount of bogwood is really too much. During the first three weeks we used to perform two 60% water changes per week and still the water had a dark brown color within 48 hours. Water parameters were checked regularly to ensure that we wouldn't experience a pH drop or an extreme softening of the water.

A photo of the tank about 7 months after its initial setup. Although many may look at the algae in dismay, in my opinion it creates a much more natural look. Click on the image for a larger picture.

Technical details at a glance


150x50x70 cm; 525 liters (139 gallons)


80x50x45 cm; 180 liters (48 gallons)


Two overflow devices by Tunze, each delivering 1500 l/h in the sump. Water passes through media for mechanical and biological filtration and is turned back by an Ocean Runner 3500 (3500 l/h) which is located in the sump.

Water flow

One Ocean Runner 3500 (in the sump) and one Ocean Runner 6500 as a stand alone pump. Total water flow entering the main tank: 10.000 l/h (14 x water volume). An additional 1850 l/h make a loop in the sump.


Three 300 W titanium heaters submersed in the sump controlled by a thermo regulator. The sensor of the regulator is submersed in the sump - before the heater compartment so it can only measure the actual temperature of the water coming from the main tank. Temperature is set to 26oC


Teco 680 chiller, capable of obtaining and sustaining a water temperature 9oC lower than the ambient temperature for this water volume. Water flow is taken care by an Eheim water pump (1250 l/h). Pump is submersed in the sump. Chiller is set to 28oC. To avoid the cool water turning the heaters on, the outlet of the chiller is placed in the compartment after the heater thermo regulator sensor.

UV lamp

Two Tetratec 4 Watt connected in a row. Water flow is taken care by an Eheim water pump (600 liter / hour). Pump is submersed in the sump.


Two warm white and two cool white 150 cm / 58 Watt fluorescent tubes with Arcadia reflectors divided in two self made fixtures. Only one fixture is on for the time being. Light duration: 12 hours.


Sand, bogwood, stones


About 50 Kg of sand forming a 4 cm layer. Sand was collected from the beach, cleaned, disinfected, washed and de-chlorinated.


Three large pieces weighting about 45 Kg and many smaller pieces of bogwood. Used to hide the inlets at the bottom of the tank as well as to divide the tank in two zones one in the front and one in the back where the fish can retreat.


Some large stones – as potential spawning sites. Being optimistic never hurt anyone.


All galvanized metal, painted white. The stand is larger than the tank to spread the weight to a larger floor area.


Wireless thermometer. Sensor located in the sump before the heater compartment.

 Filter material

Thick floss for large particles (a large bag), ten liters of Eheim Substrat, seven liters of Ehfi fix and five liters of Ehfi Mech. Activated carbon was added during the first week to absorb some of the brown color released by the bogwood. It was removed after that. One of the filters that was working on the previous tank which held the fish was also operational for four weeks.

Above: The tank as it looks now (November 2004), eight months after it was setup (see photo below). Algae has grown everywhere and gives a more "natural" appearance to it (in my opinion anyway). Click on the images for the high resolution pictures.

Update > A recent photo of the Paretroplus maculatus tank (November 2005). All the specimens are larger than 20 cm now with the largest one measuring 22 cm TL. Two pairs have formed and the tank already looks "smaller" despite its actual volume. The plan is to build one more tank (a 2 meter one) which will become the home of the 6 P. maculatus (the other 4 are thriving in the hands of Thanassis Moschou, in Drama). This tank will become the final home of a pair of Cichlasoma festae.

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