Are African cichlids meat eaters?

Which fish keep its eggs and larvae in its mouth?

The fishes which keep their eggs and larvae in their mouths are called mouth breeders. This habit is present in some marine cat fishes and in the family of the fresh water fishes called Cichilidae to which belong the fish Tilapia. In the case of c…

What happens to the well developed yolk-bearing larva of fish?

The well developed yolk-bearing larva transforms directly into the juvenile which starts feeding on exogenous food. The choice of the most appropriate method for sampling eggs and larvae is aided by knowing the spawning habits of the fish species and also a knowledge of the habitat in which the eggs and young occur.

How many times has mouthbrooding evolved in South American cichlids?

Similarly, only around 30% of South American cichlids are thought to retain the ancestral substrate-brooding trait. Mouthbrooding is thought to have evolved individually up to 14 times, and a return to substrate brooding as many as three separate times between both African and Neotropical species.

Why are marine fish eggs and larvae important?

Marine fish eggs and larvae have received more attention than those of freshwater fish because of their greater importance in stock assessment and the recruitment problems associated with over-fishing. For this reason many of the methods used by freshwater fishery workers have been adapted directly from marine work.

Is it possible to catch fish eggs and larvae?

However, the eggs and young of fish do not have this interest and until recently there has been little development of methods specifically to catch freshwater fish eggs and larvae.

How many times has mouthbrooding evolved?

Mouthbrooding is thought to have evolved individually up to 14 times, and a return to substrate brooding as many as three separate times between both African and Neotropical species.

What determines the buoyancy of a fish egg?

From specific gravity measurements of marine fish eggs salinity appears to be the only determinant of the buoyancy indicating that the thermal expansions of the fish egg and the ambient seawater are equal.

What determines the distribution of fish eggs in the ocean?

The vertical distributions of fish eggs across the world oceans display a wide variety of distributions and adaptations by selection of spawning sites and evolvement of egg buoyancies. Spawning depth, hydrographic profile, egg specific gravity, and egg stage are key information when investigating vertical egg distributions in the field.

Can we catch fish eggs and larvae by electric fishing?

Voigtlander and Wissing (1974) caught young and yearling white bass Morone chrysops down to 48 mm by electric fishing with 230 V A.C. Although marine biologists have considerable experience of catching fish eggs and larvae quantitatively, much of it is not relevant to the freshwater environment.

Are all eggs fertilized in fish?

Not all eggs are fertilized. Spawning in fishes varies, depending on the species. While some fish spawn in intervals, some spawn annually and there are some fishes which spawn once in a while. Fishes are over 450 million years old vertebrates and have constantly evolved over the years to adapt to any living conditions.

Can a marine biologist catch fish eggs and larvae?

Although marine biologists have considerable experience of catching fish eggs and larvae quantitatively, much of it is not relevant to the freshwater environment.

How does feeding affect behaviour in fish larvae?

Feeding fish larvae are more active and swim faster and longer than those that are not feeding. Issues frequently targeted in behavioural research are activity rhythms, swimming patterns, foraging and prey search, and prey capture efficiency.

Is now the time to investigate fish larval biology?

Several factors indicate that now is the time to investigate fish larval biology. Firstly, this field has become more accessible for experimental exploration thanks to the advances of recent years in culturing marine fish species. It is now possible to investigate natural larval responses under controlled laboratory conditions.

How do young fish avoid capture?

In several species, for example pike ( Esox Lucius) and many cyprinids, the young have an adhesive organ on the head and while the yolk-sac is being absorbed, they attach themselves to plants. However, if the plants are disturbed, for instance by a sampling device, they are able to move to another site and so avoid capture.

Is there information on the early development of freshwater fishes?

information on the early development of the freshw ater fishes. So it is necessary to undertake understand the biological clock and cultural te chniques of these species (Rahman et al, 2009). to determine an organism’s ancestral forms.

How much water flow is needed to incubate eggs?

The amount of water flow necessary for proper incubation of fish embryos depends largely on egg density (how heavy and large eggs are in water). Some fish eggs are quite dense and sink to the bottom when released. Other eggs become buoyant as they “water-harden” and free-float in the water column or at the surface.

What is the specific gravity of water in fish eggs?

Lipids have the lowest specific gravity; typical values of fish oils are about 0.920 g cm -3. The specific gravity of water in fish eggs is determined by the osmotic concentration or osmolarity of the water. As mentioned above, teleosts keep the salinity of the body fluids approximately constant [ 17 ].

How does salinity affect egg distribution in the ocean?

In coastal regions where salinity increases with depth, and where the major fraction of the fish stocks spawns, pelagic and mesopelagic egg distributions dominate. However, in the larger part of worlds’ oceans salinity decreases with depth resulting in different egg distributions.

What determines the vertical distribution of fish eggs in the ocean?

Here, the principles of vertical distributions of fish eggs in the world oceans are presented in an overarching framework presenting the basic differences between regions, mainly coastal, where salinity increases with depth and the major part of the world oceans where salinity decreases with depth.

How can I find the distribution and temperature range of fish species?

The distribution and temperature range of fish species were obtained from FishBase 35 by searching the combination of genus and species name. For each species, latitudes for northern and southern edges of their distribution were recorded.

How are fish distributed in the world?

Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other.

How do you find the specific gravity of a fish egg?

To summarize the present paragraph on egg buoyancy: the in-situ specific gravity of a fish egg, ρeggD, can be expressed as a function of the in-situ temperature, T D, at the depth D where the egg is located and on the salinity of neutral buoyancy measured in the laboratory, SL. Hence, ρeggD = f (TD, SL).

How does buoyancy act on plankton?

Buoyancy acting on plankton, i.e. the difference in specific gravity between plankton and the ambient water, is a function of salinity and temperature.

How to choose the best method for sampling eggs and larvae?

The choice of the most appropriate method for sampling eggs and larvae is aided by knowing the spawning habits of the fish species and also a knowledge of the habitat in which the eggs and young occur. A comprehensive account of fish spawning habits arranged as a taxonomic survey has been given by Breder and Rosen (1966).

What is the function of the egg yolk layer in fish?

This layer surrounds the yolk and cytoplasm (ooplasm). The yolk is present in considerable quantity in lungfish, Neoceratodus and Lepidosiren. The quantity of yolk is more in cartilaginous fishes such as Acipenser. Egg size and yolk contents are independent variables.

Are fish eggs planktonic?

Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply.

What eats fish eggs and larvae?

Both eggs and larvae are themselves eaten by larger animals. Fish can produce high numbers of eggs which are often released into the open water column. Fish eggs typically have a diameter of about 1 millimetre (0.039 in). The newly hatched young of oviparous fish are called larvae.