Poll

Cyanobacteria

Cyanobacteria are a gram-negative bacteria which is often classed under algae by fish keepers because of its ability to photosynthesise. It spreads across all surfaces, coating plants in a layer of slimy-looking goo. In fact, the goo may actually feel quite solid, rather than slimy. There are many different species of cyanobacteria, including the Spirulina genus, which is used in the manufacture of some vegetable based fish foods. The cyanobacteria commonly seen in the aquarium are not as useful, unfortunately, often being from a range of species which specialise in nitrogen fixation. Nitrogen fixation is the conversion of N₂ into NH₃, this may potentially cause problems. Some species of cyanobacteria are also capable of producing cyanotoxins, which may harm fish.

The biggest dangers cyanobacteria poses in aquariums is killing the plants by physically cutting off light and using up oxygen.

Since the plants can reduce the chanced of the bacteria reappearing in the future, it is important to make sure that the plants are not killed off by physically removing as much of the cyanobacteria as possible. The next step is the treatment. There are two options:

• Blackout: clean off as much bacteria as possible, then cut out all light for at least a week. This method focuses on the bacteria being starved of light and nutrients (as no fish food would be going into the water). It may take a few attempts to truly kill off the bacteria and each attempt should also be followed by removal of any remaining bacteria. A week without food will not harm most tropical fish, so this method is relatively safe and sound.
• Antibiotics: an antibiotic which acts against gram-negative bacteria may kill the bacteria. This option needs to be considered with care because most medications are harmful to aquatic animals (the extent to which this is the case depends on many factors, including the pH of the water). Some antibiotics which are sold as treatments for fish will also harm the gram-negative nitrifying bacteria.

Given that there are no fish in the aquarium, I decided to try the antibiotics method. A quick search on the internet showed me that eSHa 2000, a generic antibacterial and anti-fungal medication which is produced by eSHa Labs, may work against cyanobactria. A further search showed that the ingredients are ethacridine lactate (antiseptic, trade name Rivanol), proflavin (antibacterial against gram-positive bacteria and antiseptic), Cu₂⁺ (antimicrobial) and methyl orange (mutagen). Since I was unable to find whether the ingredients acted against gram-negative bacteria, I emailed eSHa to ask. This is the reply I received:

eSHa 2000 does work against [gram-negative and gram-positive] bacteria but not against all bacteria.

Kind regards,
[…]
eSHa Labs

I proceeded with a standard treatment, following the instructions on the medication. On the first day, I added 14 drops, followed by 7 drops on each of the following days. By the second day, most of the bacteria was gone. It has now been one week and there are no signs of cyanobacteria left, so I can conclude that the medication or some other combination of factors have resulted in successful treatment.

Sinking the wood

A friend of mine told me that his red moor wood took 4-6 weeks to sink, so I decided to give mine a little helping hand by placing a fish-bag-full of inert rocks on top of it, after moving it into position. On my second attempt, about a week later, I was able to remove the bag of stones, with the wood not floating up. I took the opportunity to move the weeping moss onto the wood, rocks and all included, as it is best when grown hanging off branches.

Daily tests: day 60

In preparation for adding fish, I decided to do a full set of tests as these would come in useful when deciding how to acclimatise the fish:

• KH: 10 ° (179 ppm)
• GH: 20 (358 ppm)
• ammonia: 0 ppm
• nitrite: 0 ppm
• nitrate: 10 – 20 ppm
• pH: 8.2 – 8.4

Wood fungus/bactria

The wood has started growing a layer of what could be either bacteria or a fungus, which is apparently common in aquariums with a higher pH. I have seen this happen on a re-used piece of mopani wood before: it usually stops growing the fluff after a while. Without analysing a sample of the fluff, it would be impossible to find out if it really is a bacteria or a fungus. I took the wood out of the aquarium and washed it off. The fluff feels slimy to the touch, but is harmless.

First maintenance

Above is the photo of the aquarium after I finished a full maintenance on the aquarium.

I started by turning off the heater and filter, and scraping all the diatoms off of the front using an expired bank card, followed by the sides and the back, although I must admit that I did not make a particularly good job of the back. I was especially careful to not catch the sand, but I think I still may have caught one or two grains which would have scratched the glass.

Next, I drained out 5-10% of the water into a bucket, syphoning up all the diatoms I scraped from the glass. At this point, I decided to clean the filter. So I took the filter out of the aquarium, which was a bit more difficult than I would expect because of the spray bar. I pulled the filter apart and started cleaning the media in the old aquarium water which I had just drained: chlorine and chloramine will kill the nitrifying bacteria that I have been growing and feeding ammonia to. In the two months that the filter has been running for, it has become covered with sand dust, including the media and the impeller. I gently squeezed the sponge in the water until I could not see any sand left on them, then cleaned the impeller, the plastic casing and rubbed the ceramic media between my hands to remove the fine sand coating which was covering it in places. Rubbing ceramic media against itself is not harmful to the filter because the vast majority of the bacteria will be inside the media. Next, I cleaned all the soft plastic as some of it still had fungus on it. I reassembled the filter and placed it back into the aquarium.

Because my tap water is hard, I have lime scale deposits around the top of the glass, inside the aquarium. I cleaned these off with some cotton wool which I soaked in spirit vinegar and then rinsed the areas with aquarium water.

Finally, I syphoned out the remaining water down to about 10 cm from the bottom. So as to not disturb the sand, I then syphoned dechlorinated and temperature matched water back into the aquarium, finishing off with a top up to get the water level right as I do not like the sound of trickling water too much. In total, I changed 36 litres of water.

Finally, I switched the filter and heater back on, managing to spray water out of the aquarium in the process, and added the new piece of wood. The flow of the filter looked much faster, now that it had been cleaned.

Daily tests: day 48 – 57 and adding wood

I’m planning to do a large water change tonight, in preparation for the fish, and I would also like some clear readings for the record, so I know how much the wood will affect the water after it is added. This morning, the readings were:

• KH: 9.5 ° (170 ppm)
• GH: 21 (376 ppm)
• ammonia: 0 ppm
• nitrite: 0 ppm
• nitrate: 80 – 160 ppm
• pH: 8.2

I expect KH, GH and nitrate to drop after the water change because my tap water readings are lower.

Unfortunately, the diatoms are still there and getting worse, so hopefully, the water change will help improve the situation. I also have a Malawi aquarium, which, for those of you who do not know, is a Lake Malawi simulation, with a lot of rockwork and no plants because the fish which live in the lake naturally graze on algae and have a habit of mistaking plants for algae, which means that most plants would not survive for long. In this rocky and plant-free environment, I also often see diatoms, and as is currently the case with this aquarium, the Malawi setup also has high nitrates, so I assume, given that the general hardness is the only other common factor between the two aquariums, that the nitrate is responsible. I have also noted the appearance of cyanobacteria, an algae-like bacteria, today. I hope this is also related to the high nitrate levels.

I performed a clean of the aquarium, including glass and filter, and changed 36 litres of water, which was approximately 80%. The water readings after the maintenance were:

• KH: 10.5 ° (188 ppm)
• GH: 18 (322 ppm)
• ammonia: 0.25 ppm
• nitrite: 0 ppm
• nitrate: 10 – 30 ppm
• pH: 7.8

The results indicate that my tap water has changed since I took the original readings: my tap water pH has dropped, while the KH has risen.

I also added the wood, right after the water changes. It has now picked up the rich red which gives it the name of “red moor wood”, but is being slow to water log.

Aquarium wood

One of the most popular types of décor for aquariums is wood. There are a number of different types sold commercially and it is possible to prepare one’s own wood for aquarium use. The most likely ones to be found in shops are bogwood, driftwood, mopani root and “red moor root”. There are also a few other types which are only starting to become available now or are not so popular too.

Bogwood and driftwood are usually solid pieces of grey to brown colour, they are usually parts of the trunk or thick branches. Mopani is more of a thick, gnarled root, a light sandy colour on one side and a rich brown on the other. “Moor root” is used to describe any wood which is composed of weaving, curly branches, usually attached to a gnarled base. Moor root often comes in colours ranging from orange to red. I have also used dead English oak branches with success, and dead heather branches and roots, but the heather tended to disintegrate quite quickly.

There are a few benefits to using wood, the biggest one being the release of tannins, which help lower pH. Soft woods, such as bogwood, are also required if plecos are kept, because plecos will feed on them. Wood can also be used to grow certain plants, such as Anubias, Microsorum pteropus and various aquatic mosses, which can be a big advantage when keeping species which like to dig.

The advantages of wood are also the disadvantages, some people do not like the tannin coloured water and the lower pH is not suitable for certain fish. Wood can also start growing fungus, this is often the case if the wood has been boiled in a bid to remove tannins: it is considerably more productive to just soak the wood in a bucket, changing the water regularly. Once fungus has appeared, it can easily be removed with a syphon or by gently scrubbing the wood under the tap.

I prepare wood by brushing off any dirt under a running tap, then adding it to the aquarium, where it should quickly become water logged, although sometimes, the wood can take a few days to a few weeks to sink.

Deciding on fish numbers

Most aquarium fish can be classed into one of three living preferences:

Schooling and shoaling:

These fish, depending on the species, live in groups that range form a few hundred to a few million individuals. Home aquariums are most often not able to hold groups that large, but the bigger the group the better it is. I usually recommend that one should aim to keep 10 – 15+ individuals per schooling species as there is no excuse to not do so if stocking a new aquarium. Unfortunately, some people find out that they have only a few individuals from a schooling species after the aquarium is fully stocked, in which case it is best to try and increase the numbers to at least 6 individuals per species or to find them a new home. In some way, fish are aware of individuals up to a point, at which the individuals become “many”. I think that 6 individuals is this point for many species. One of the most important functions of schooling is to protect the individual fish from predators, either by letting the weaker fish in the group be picked off first (as easier prey) or appearing as one larger fish. The main difference between schooling and shoaling fish is that shoaling fish will normally only swim in a tight formation when threatened, usually going about their own business (for example, Trigonostigma heteromorpha). On the other hand, schooling fish (such as Paracheirodon innesi) will spend most of their time swimming close together, even to the point of facing the same way. The group includes fish like tetras, rasboras, danios, barbs, many loaches and rainbows. One unusual member of this group is Neolamprologus brichardi, a shoaling cichlid.

Small groups:

There are a few different variations of small groups which can be found. These include small groups of social fish, which do not have much social structure (such as livebearers) or which have a specific social structure (for example, cichlids); closely knit family groups; pairs of breeding male and female couples; harem groups of one male and a number of females (often seen in many Apistogramma species), or quite rarely, one female with some males. As with schooling fish, small groups provide security for individuals. For some mildly aggressive species, such as Pterophyllum scalare, it may even be possible to keep them peacefully only individually, in proven breeding pairs or in small groups of more than 6 individuals because the dominant fish can then spread the aggression over multiple individuals, instead concentrate it on a single one.

Solitary:

Some of these fish are too aggressive to keep with any others of their own kind, and in some cases, even with other fish which would occupy the same area inside the aquarium, while others simply do not interact with one another on a regular basis. This group includes some loaches, cichlids and gouramis.

It is quite important to try and keep the fish in appropriately sized groups as some may otherwise display odd or aggressive behaviour. The easiest way to find out appropriate stocking numbers is to research the conditions in which the species is found in the wild.

Some basic research showed me that Danio margaritatus and Yunnanilus sp. ‘rosy’ is a peaceful, mid-water schooling fish, which automatically means that I should be considering 10 individuals per species. This is a good number to start with, and there is always the option of adding more later.

Pseudosphromenus dayi, on the other hand, is a solitary fish which breeds in pairs. Males may occasionally be persistent, so I decided that it is better to have 1 male and 2 females, to give the females a bit of a break in case of uninvited attention.

So for my first “final stocking”, I will be aiming at the following:

• 10 × D. margaritatus
• 3 (1m 2f) × P. dayi
• 10 × Y. sp. ‘rosy’

It is very common for final stock to evolve with time, which is why I am referring to this as my first one. As for how I decided on the total number of fish? That is rather difficult to explain as there are no set rules, nor have I seen any good guidelines. I chose the number based on my experience and I always base my decisions on adult size. The stocking numbers are also affected by the amount of plants in the aquarium as they will use up ammonium. For an aquarium which is 60 × 30 × 30 cm in size, I would normally expect to stock between 6 individuals of the larger species I list and 25 individuals of the smaller species. I would also stock conservatively if I pick female livebearers because they will drop fry and it is best to reduce chances of overstocking.

The best advice I can offer on stocking is to not stock more than one feels comfortable with, even if others say that the aquarium will take more fish, and if one is being advised to stock less than one plans to, to try the lower stock first.

Pseudosphromenus dayi

Since I am now unable to collect the Danio margaritatus, I will be moving the Pseudosphromenus dayi to this aquarium instead. This anabantoid comes from Kerala, the most south-western Indian state where air temperatures range from 15 to 36 °C, which I assume corresponds to water temperature of 16 to 34 °C. The fish have been found in fresh and brackish water, usually in lentic conditions, and may be very common in Chalakkudy River, Muvattupuzha River and Periyar River. There are some claims that this species can also be found in south-east Asia, but this is very likely to be a mistake caused by a mislabelled P. cupanus holotype.

As with other Osphronemidae, P. dayi possesses a labyrinth organ as well as gills, which allows it to breath air instead of extracting oxygen from the water as most other fish do. The labyrinth organ is located in the gills, at the first gill arch. I have read of research done into the breathing of Betta splendens, another labyrinth fish, where results showed that without access to air, the fish suffocated, so it is safe to assume that fish which have a labyrinth organ do require access to air at all times.

Apparently, the fish can grow up to 75 mm, although one of my females is currently at 30 – 35 mm and the male is around 35 mm at, by my estimate, at least one year of age. Fish are normally measured nose to base of tail for consistency, as tails can vary in length between individuals; with the tails included, the same female is around 45 mm and the males is close to 50 – 55 mm.

Mature males of the species have more orange throats, considerably elongated and pointier dorsal and caudal fins, and slightly elongated anal fin compared to females. Juveniles are almost impossible to sex unless the males’ fins have already started growing longer and I have found that the orange throat is usually more noticeable when the fish are ready to breed.

These gouramis are not shy, but do require plenty of plants as they spend most of their time under leaves. I currently have three of these fish in a 420 litre aquarium, where each one has taken up residence in a specific group of plants. One female has chosen a large Anubias barteri (spending most of her time under one of the broad leaves or swimming thought the roots), the other female has taken up residence in some plants which have floated to the surface, while the male lives in a patch of Cryptocoryne wendtii ‘brown’ (I often see him wrapped around one of the leaves). Flow does not seem to matter much to them as the females are both in areas where there is almost none, while the male spends much of his time about 15 cm away from a circulation pump, which is pointing directly at him. They are not strong swimmers, so I would say that a densely planted aquarium or one with low-flow areas is compulsory. The aquarium is 60 cm tall, but all three fish spend their most of their time either within 15-20 cm of the bottom or inside floating plant clumps, with the exception of feeding times, when they happily come out into the open.

As with many other gouramis, P. dayi is a surface feeder and their natural diet includes insect larvae. In an aquarium environment, they readily take all prepared and live foods of appropriate size. They are a slow feeder which takes its time to come out for the food, so it is important to make sure that they receive their portion of the food, especially if they are kept with fish which are known to be greedy for food.

P. dayi are compatible with most peaceful, community species, with the usual exception of other labyrinth fish and those which are big enough to eat them. Because they are a slow species with a flowing tail, they will make prime subjects for abuse by fin-nipping species, so it is best to avoid those.

The species breeds in pairs, with the male building a bubble nest inside a cave or under some leaves. The female lays approximately 200 to 300 eggs, which sink to the bottom and are collected by both parents before being spat into the nest. The eggs are guarded by the male and will usually hatch within 24 – 36 hours. After a few days, the fry use up their yolks and become free swimming.

P. dayi are currently classed as vulnerable by the IUCN, so it is worth looking for aquarium bred specimens over wild caught ones. Deforestation and agricultural activities, man-made pollution, mining and destructive fishing are the main threats to their habitat.

After more than a few hours of searching, I finally located the journal that the species was originally described in on Google books, but I am unable to find somewhere that I can download it from. For reference, the species was originally described as Polyacanthus cupanus dayi by W. Köhler in 1908. The paper, Untersuchungen über das Schaumnest und den Schaumnestbau der Osphromeniden, was published in Blätter für Aquarien- und Terrarien-Kunde, Stuttgart, volume 19 (pages 392-396). If anyone has a copy of it, please let me know as I am interested in reading it.