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Megalechis thoracatum

formerly: Hoplosternum thoracatum

Synonyms: Callichthys thoracatus, C. longifilis, C. personatus, C. exaratus,
Hoplosternum thorae, H. longifillis, H. magdalenae.

(©1997 by Kaycy Ruffer)

In the subfamily Callichthyinae some taxonomic and nomenclatural changes have already been made. It was found that Hoplosternum was also a paraphyletic assemblage. Two new genera were erected to keep each clade monophyletic. Hoplosternum in the "sensu stricto" is the sister group of Dianema. Two other species formerly assigned to Hoplosternum, the Hoplosternum thoracatum Group, represent the sister taxon to the above clade, and were transferred to the genus Megalechis. Four other species composing the Hoplosternum pectorale Group, are the sister taxon to the above clade, and were transferred to the genus, Lepthoplosternum. Callichthys, with only one currently recognized species, C. callichthys, is the most basal member of the callichthyines. The controversial genera Cascadura Ellis, 1913 and Cataphractops Fowler, 1915 were found to be synonyms of Hoplosternum.1

These fish are found in shallow, muddy waters dense with vegetation. Schools of as many as one thousand may be found in waters close to habitation, especially in areas where waste water is deposited. Trinidad; Guyana; Martinique; Venezuela; Brazil; Peru; Paraguay.2 They were first found in 1911, by Vereinigte Zierfischzuechtereien, Conradshoehe, near Berlin, Germany.

I received my first Hoplos in the spring of 1994. I was given three babies approximately 1¼" long from a friend of mine, Linda Friewald, who was going to shut down her fish room. These were the last Hoplos that she had. It took a year before they were old enough for me to sex. 

The way to sex Hoplosternum thoracatum is to look at the first hard ray of the pectoral fin. The male will have longer more pointed pectoral fins and the first ray will be thicker and have a reddish-orange tint. The females pectorals are short and rounded. I had two males and one female. I set the female up with one of the males in April of 1995 in a 15-gallon long tank with a sponge filter. The water was from the tap and the pH was 7.5 and the hardness was 80 ppm’s. I fed the pair live tubifex worms and frozen blood worms. Notice the long barbels of this species. This species find their food by odor. Dropping a clump of tubifex worms in the tank can be spooky to the fish if the worms touch their body. Once the worms are on the bottom of the tank and the fish get the ‘odor’ of the food, they go right for it.

I was quite surprised to find they had spawned and the male had eaten the eggs instead of caring for them, which in this species the male is the total care giver for the eggs and fry. After spawning the male will chase the female away.

I decided to switch males so that I would have a male that did not eat his eggs. That was the best decision I ever made. This new male and the female spawned in May of 1995. The female laid her eggs all over the back glass of the tank. I read some literature on the Hoplos and found they like to spawn like the labyrinth fishes. The Hoplos build a bubble nest under some form of structure and since I didn’t have any such thing in their tank, they spawned on the tank glass!

After placing a piece of a styrofoam lid, 4" x 2", on the surface I would find a bubble nest underneath the styrofoam that the male had built.

It was no easy task trying to catch this pair spawning. No matter how early I got up in the morning to watch them, they were already finished spawning. I actually stayed up for 24 hours straight to catch them. Nothing. Once I went to bed they spawned! I almost gave up on catching this pair spawn until I had one other idea. I left a light on their tank for three days straight. The only thing I can figure is they spawn as soon as the sun starts coming up in the mornings. They also didn’t like being watched.

After the third day, I decided to go into the room and see how the pair was doing. BINGO! I was able to watch the pair spawn! This species actually uses two methods for spawning. One is the ‘T-Position’ that is commonly known to happen with Corydoras species. The female will put her head towards the side of the male just behind his pectoral fin. It looks like the male clamps his pectoral fins around the female’s mouth. The female will then put her two ventral fins together to make a basket in which she releases one to four eggs. After dropping the eggs into her ‘basket’ the male leaves and goes to tend to his bubble nest he has built under the piece of styrofoam. After a few minutes the female regains her composure and heads for the bubble nest where the male will leave and she will turn upside down and press her ventral fin ‘basket’ into the bubbles and then release her eggs after searching for the perfect spot to lay them. When the female is finished and leaves the male returns. The male continues making bubbles to replace bubbles that have popped and to tend to the eggs. I told myself I would remove the eggs for the first few spawnings.

I lifted the styrofoam platform from the water and I couldn’t believe how many eggs there were. They were quite large and yellowish in color. They were also VERY sticky. I would sometimes have trouble getting the eggs off my fingers when I would remove the eggs to place in a net. Since the eggs were very sticky I was able to stick them to the net sides without them clumping at the bottom of the net. This net actually held 900 + eggs from one spawning! The eggs are about three days old and have become dark with the developing embryos.

After several attempts (six to be exact) of trying to hatch and raise these Hoplos in my tap water with fatal results I finally tried using soft water. I had been breeding a few species of Apistogramma at the time so I had an R.O. unit at my disposal. I would collect the eggs and scrape them gently off the styrofoam and place the eggs in a net and hang the net in a 10 gallon tank that contained a sponge filter and the net. I finally had good results.

I kept breeding the Hoplo pair in the tap water and hatching the eggs in soft water. I was soon running out of room to raise the fry. I was in a one bedroom duplex and the bedroom was my fish room and contained eight 55-gallon tanks, twelve 20-gallon tanks, three 30-gallon tanks, twenty-eight 10-gallon tanks and one 15-gallon long tank. This pair continued to spawn about every three days and I was surprised to get at least 900 fry each time! I do not mean eggs. I mean actual fry.

The male Hoplo also had an attitude. My fault, but it was interesting to see some of his natural defenses for protecting his eggs. When the male would move the piece of styrofoam to where he wanted it in the tank, usually at the end with the most water current from the sponge filter, I would move it to the opposite end of the tank. I would also do this to him when others would come over to to see my fish room to show them what he would do. The male would come to the other end of the tank where I had placed his spawning material and he would turn upside down facing the other end of the tank where he wanted to go and would ‘hold’ onto the styrofoam with his ventral fins and he would ‘swish’ his tail in the water to move the styrofoam back to where he wanted it. Another thing I would do, and it was only because I was removing the styrofoam to collect the eggs that I first noticed his reaction, was to reach in to get the spawning site without really grabbing it and the male would come to the surface, turn upside down and in a flash ‘flick’ his tail out of the water supposedly to chase me away.

I really did enjoy watching this pair. Especially the male and his actions when he had eggs to protect.

It took five days for the eggs to hatch and another seven days for the fry to be free swimming. Once the fry were free swimming I would feed them newly hatched brine shrimp. After two to three days of eating in the net I would turn them loose in the 10-gallon tank from which the net hung. They grew rapidly. After about 2 weeks I would then start supplementing their diet with finely ground flake food.

This is a very interesting fish and can be kept in non-aggressive community tanks. They will move sand with their barbells in search for food or come to the surface and turn upside down and eat food from the surface.

References 1: Reis, R.E. 1997. Revision of the Neotropical catfish genus Hoplosternum (Ostariophysi, Siluriformes, Callichthyidae), with the description of two new genera. Ichthyol. Explor. Freshwaters, 7(4):299-326 Roberto E. Reis E-mail: reis@music.pucrs.br Laboratório de Ictiologia Museu de Ciências e Tecnologia da PUCRS Caixa Postal 1429 90619-900 Porto Alegre, RS Brazil Page copyright © 1996 Roberto E. Reis, First online 29 April 1996, Last modified 14 May 1998

References 2: Baensch Aquarium Atlas Vol 1, by Rudiger Riehl, Hans A. Baensch, 1997, Microcosm Ltd.

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