by Marina Parha and George J. Reclos , uploaded January 15, 2009
They are small, they are elegant and they are Hypancistrus. That is enough to qualify them for a place in the hearts and the tanks of most fish keepers enamoured with Loricariids, me included. Yet they are not a fish you will see often in a LFS. My colony arrived at Pier Aquatics in two separate shipments, shipped about 3 months apart, following a special request. The reason for the two shipments is obvious: to the extent possible I prefer to minimize the risk of getting siblings.
1. Adult male
The fish that arrived were not yet sexually mature; I prefer it this way. It gives the fish a chance to adapt to their new environment and get well settled prior to attempting to spawn. Hypancistrus are relatively easy to sex from a young age by looking at the shape of their genital area; a V shape indicates a male while a U shape indicates a female. While this rule is not necessarily applicable to all and every Loricariid it has served me well to-date. Admittedly some individuals are somewhat difficult to sex in that some of their morphological characteristics suggest they are male while others imply they are female. This is unimportant considering the size of a colony. I usually get 3-4 males and 6-8 females which allows for a comfortable margin of error in sexing.
The fish were rather young so I put them in a Hypancistrus tank to grow out. The tank was 149 litre (122 x 33 x 37 cm, l x w x h) and was serviced by 2 Blue Modular internal pumps (1200 litre p/h each) set on low. Other peripherals included a Tetratec APS 400 delivering air via two long outlets placed along the back side of the tank and an appropriately sized heater keeping the water temperature at 27°C in winter and 29°C in the summer. The substrate was neutral coloured aquarium sand (quartz). Tank furniture included slate caves measuring 10 x 3 x 2.5cm (l x w x h, internal dimensions), bogwood, slate formations towards the back of the tank and floating Ceratofullum demersum. The tank was shared with a colony of L260s and a colony of L174s, both equally young and growing up.
As the tank was placed under a window there was no need for a lighting unit; plenty of algae and the Ceratofyllum were growing nicely due to the sunshine entering the tank from above. Similarly the layer of algae and Ceratofyllum provided a nice shade for the fish below. In terms of tank maintenance I performed a 60% - 70% water change weekly over a period of 45 minutes using a continuous flow system (clean water enters one side of the tank while tank water gets removed at the other side of the tank). During the water change 50% of the filter media (sponges) get replaced with clean ones.
The water chemistry of this tank was similar to this of most of my other tanks: pH 7.2 - 7.6 with the addition of Sodium bicarbonate, KH 3, GH 4-5. The fish were fed daily a mixture of dry foods consisting of Blue Line Basic / Marine and Discus 122, Ocean Nutrition 1 (small) and Dr Basleer Tropic (L initially followed by XL as they grew up). Once or twice a week they had a treat of frozen cockle, chopped mussel, chopped prawn, frozen bloodworm, artemia, cyclops or daphnia (these were offered alternatively). Hypancistrus are not great lovers of green food however I did include vegetable matter in their diet once a week in case they needed it. Admittedly I have never seen them eating it; on the other hand I have never identified any food left overs next day or smelled food decomposing in the tank.
A year later the fish had grown well. I moved them to a 90 litre dedicated tank, located very close to the place their original tank was. The tank had, on the main, the same specs as the grow out tank. There were three slate caves, one for each male, and plenty of wood for the females to hide under. The differences from the previous set up were:
Eight months later the fish were showing clear signs of sexual dimorphism which meant they were sexually mature. I was a bit concerned about one of the females, "Betty", who chose a very odd place to live.
In addition to being upside down all the time "Betty" was staying at a location which was in the open and well lit. That was odd as there were plenty of suitable hiding spaces available in the tank. I have not seen this fish move from this location for over a year and a half now other than on one occasion where I noticed she was "missing". But more about this later.
By that time the three males have appropriated a cave each and all seemed to be going swimmingly. The bigger male, "Sunny", who I assumed was the alpha male, got the cave further away from the pump; the way this tank is set up that meant that this cave was the one less hit by the current as the water reverses in front of it. The other two males got the caves next to this in order of size and age (the second male got the middle cave and the smaller male got the cave nearer to the pump). I waited until the Christmas holidays were over and started preparing the colony for a spawn. That meant going through the usual routine of feeding frozen bloodworm twice weekly, raising the tank temperature to 30°C and stopping all tank maintenance for 4 weeks. Following this I did a massive water change(over 80% of the water over a period of 2 hours) using fresh water about 3 degrees cooler than the existing tank water and cleaned the filter media. I let the temperature rise to 28°C and waited to see what happened.
I did not like what happened. Three days later I found the smaller male dead. There was no sign of disease in the tank, the other fish were absolutely fine and the strange thing was that the body was in the open, pushed up against a corner. When fish feel unwell they usually go to hide; I would expect this male to have died in his cave if something was wrong with him. Instead the position of the body as well as the location it was found indicated a fight. So I let the colony settle by avoiding the scheduled follow up big water changes for a while.
Two months later I tried again. This time I also lowered the pH and turned the lights off for a whole week, then started turning them on gradually. The colony did not respond. In May of the same year I considered the problem may be the high water turn over in this tank, so I lowered the flow to the minimum. This did not have any immediate result either. During all this time the males remained fixed in their caves while the females were invisible under the wood.
5. Overview of tank. The diagram shows the water flow and the positions of the caves
At the beginning of July this tank had to be moved to a different location; we started a big extension of the house and the builders needed access to the location where the tank was. George and I emptied the tank leaving the fish with only about 10% of the water in it, then moved it to a different room where we filled it up again. The main difference between the previous location and the new one was the level of light entering the tank. Though ambient light could get through the front glass there was no natural sunlight getting inside of the caves at an angle in the new location. In both locations the tank faced westwards; while in the former location it was leaning against a single course brick external wall in the latter it was leaning against an internal wall. Given the fact that the move took place in the summer this would not have made any difference in the overall temperature of the tank.
Towards the end of July all the fish in the house were extremely upset. Due to the building work there was a lot of noise and vibration for long periods of time. The amount of brick and plaster dust in the house was unbelievable. Though the tanks are covered, dust did get in the water. Under the circumstances all we could hope was for the fish to get through this ordeal well.
I was away all of August. During this time there were no water changes though the tanks did get a top up if water evaporated. When I am not around the fish get fed once every three days staple food only. I returned on the first of September and started servicing all the tanks, checking that the fish were in good condition. When it was the turn of the L262 tank I noticed a recently hatched fry at the entrance of "Sunny"'s cave. I was thrilled about the spawn and made some notes of the circumstances under which it took place.
6. Fry outside its father's cave. On the right hand side the mother, "Betty", in her usual resting place
7. A well fed youngster
Due to the building work the available space in the house is extremely limited; getting the fry out of their parents' tank to grow separately was out of the question. This had a further drawback. This fish is a recluse and the fry are well versed to hiding from the word go; photo opportunities were next to zero. I occasionally did see some of the fry getting in and out of their father's cave but the majority were well hidden under the wood and to all intents and purposes invisible.
I spend a lot of time observing my fish; different markings allow me to identify who is who, which is why they all have names. In turn, naming the fish allows me to identify lineage as most of my colonies have more than two breeding pairs. On this occasion I missed the female going in "Sunny"'s cave. I did notice, however, that a female went to occupy the space over his cave shortly after the spawn. I saw her leaving and returning there over a period of a week, resting on the top of he cave under an overarching piece of wood. The female occupying this space is usually the partner of the male in the cave.
At the beginning of October, two months after the first spawn, I noticed "Betty" missing from her usual spot. This was extremely unusual so I decided to look for her in the tank. With the help of a torch I checked under every piece of wood but I found no sign of her. When the torch shone, accidentally, inside "Sunny"'s cave, I saw he had a female locked in. Next day "Betty" was back in her usual place; George and I lifted the top of "Sunny"'s cave and we saw him guarding eggs.
That was a surprise indeed. It was obvious that "Betty" chose that piece of wood for her resting place as it was the closest possible resting place to "Sunny"'s cave. The female resting occasionally on top of "Sunny"'s cave is clearly a rival, though I have never seen "Betty" chasing her off. The egg ball had about 20-25 eggs; the eggs were surprisingly large considering the adult size of the fish. If that is the average size ball then the survival rate of the fry in the tank is excellent. With regards to hatching time, it appeared that the fry hatched 5-6 days after egg laying at 28°C. I cannot be positive about the hatching time as I did not take the egg ball out of the father's cave; I have checked the cave regularly with a torch. It is possible that the fry I saw were either the first or the last ones to hatch.
Around the same time we noticed some commotion around the second male's cave. Three females lined up to win his affections; the male showed his preference to one of them, "Natasha", by getting out of his cave and sitting close to her, head to head, every time she was approaching. One of the rival females was quite persisting; this seemed to put "Natasha" off from entering the male's cave. Finally the male decided to take action. On one occasion that "Natasha" was hesitating in front of his cave he chased her rival off. When he returned the paired disappeared inside the cave to spawn.
"Natasha" manifests a behaviour worth reporting when it comes to spawning. She does not like any other fish, including fry, near her males cave prior to her entering to lay eggs. On a number of occasions I have seen her chasing fry away. She will approach them and gently push them away with her head until they move further away from the cave. I have not seen any other female or male Hypancistrus do this. In the main, adults usually ignore fry or juveniles.
Parental care varies amongst male Hypancistrus. Some males will get their fry out of the cave quite quickly. Others will keep them in the cave for longer periods of time. With few exceptions males will not allow their female to enter the cave and lay eggs for as long as fry are in their cave. It is thus possible that "Natasha" only chases away her own fry for fear that if they re-enter their father's cave she will not be allowed in to lay eggs. This is a speculation, as the fry from both pairs are currently growing together in this tank so I have no way to know if "Natasha" is chasing away all the fry or just her own.
14. Fry feeding on pellets for adults
In my other Hypancistrus tanks I have noticed that a lot of the fry collect behind or under the pumps. I assumed this was due to a combination of the low water flow in these spots as well as the fact that I put the food directly in front of the pump nozzles. Most of the pellets get carried away by the flow and they get spread evenly in the tank; some go directly behind and under the pumps so the fry who collect there are the first to eat without having to compete with adults. In this tank, as the pump is tilted, I place the food at the opposite side of the pump; this is where the fry collect. It is worth checking if this observation has a wider application. In this case encouraging designated fry areas in a tank could potentially make collection easier. Fry seem to have no problems eating the big pellets intended for the adults.
The growth rate of the fry is comparable to that of Hypancistrus zebra, it is painfully slow. Photographic evidence indicates that the fry are quite well fed while observation, mainly after lights out, verifies they are also quite active. Once over two months old the fry do occasionally venture out in the open although on the main they prefer to keep themselves to themselves.
So far both pairs spawn regularly, once every 6-8 weeks. This colony has only recently started spawning so I have not yet had the opportunity to observe an annual spawning cycle. It is likely that after a number of spawns the pairs will take a rest, then resume spawning activity again. It appears that both males spawn with their preferred female only. That calls for four more adult males to be added to this colony as my four single females are heavily gravid and desperately trying to get in the males' caves.