Images of Wigglers

Eggs and Newly Hatched Larval Fish


 
 In the images below I tried to capture the development of the fish from fertilized egg through a larval stage called wigglers. The highest magnification photographs of the eggs and wigglers were made with the subject on microscope slides. The slides were put over a colored and textured background for artistic effect. Photographs of eggs and wigglers on the breeding slate were made while the slate was in the aquarium. The high magnification required limited the depth of field of the image. Free swimming fry were photographed in a "micro aquarium" made with microscope slides and aquarium sealant. 


The development and growth of tropical Angelfish 

click on the pictures below to see the full-size image 
This egg is 60 hours old and almost ready to hatch. Inside the egg the larval fish is curled around the yolk sack. The head of the fish is at the top of this image. Under a low power microscope the beating heart is clearly visible and one can easily observe blood flow through the unhatched fish (the egg wall and fish body is quite transparent).

Fungus is a threat to the eggs before hatching. The egg on the right has been attacked by fungus. I add methalene blue to the water immediately after the eggs are laid to control fungus.

Typically the parents lay eggs on a breeding slate or on the leaf of a plant. If the tank has no other occupants good parents will care for the eggs and raise the fry. Occasionally I have had a mating pair watch over the eggs even in a community tank but not many fry will survive in such an environment. When I want to raise a batch of fry I move the slate to an empty (well cycled) tank immediately after spawning. A bubbler will keep oxygenated water flowing over the eggs.

After hatching, the fish enter a larval stage and are called "wigglers". The wigglers remain attached to the slate by a sticky filament which emerges from their head. I don't know the technical name of this appendage. It drops off when the wigglers become free swimming.

This wiggler hatched 24 hours ago. In the larval stage the fish live off of a yolk sack and do not eat food. The eyes and internal organs are still developing at this point.

This wiggler, 48 hours after hatching, has consumed most of the yolk sack. It will be free swimming in about another day. The eyes are well developed and respiration can be observed (with a magnifying glass).

Click here to see close up photographs of free swimming fry.

 

Once the fry are free swimming (three to five days after hatching, depending on the water temperature) they will need to eat. For the first day or two they can survive eating microscopic organisms (infusoria) in the tank. Some breeders will add yolk from a hard boiled egg pressed through a fine cloth into the tank. The best food source, however, is freshly hatched brine shrimp. 
 

I use a home made hatchery. For close up photographs of newly hatched brine shrimp, information on how to build a hatchery and hatch them, please click on the link below. 


Information on hatching Brine Shrimp

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