The goal of each serious aquarium keeper is more than simply to display some pretty fish. The serious aquarium keeper hopes to create a little environment to present
some of nature's most special and spectacular creatures, fresh and brackish water tropical fish. Unfortunately, many species of fish
are endangered or on the brink of extinction because of mankind. The destruction of rainforests, the damming of
rivers, the polluting of rivers, and the introduction of non-native species are acts which most directly affect
Tropical rainforest waters are
the home to the majority of freshwater fish species.
The Amazon Basin alone has over 2300 known species and possibly as
many unidentified species; but the world's rainforests are threatened. The rainforests are being reduced at
a rate of about 1 acre per second or 116 square miles a day (Orr 7), translating to 42,340 square miles lost a
year. Each day, 40 to 250 species become extinct (Orr 7), and each year, as many as 92,000 species are
lost. Although tropical fish make up only a tiny part of the species lost to extinction as a result of
deforestation, they are still threatened daily by rainforest destruction. The destruction of rainforest affects
fish species by loss of habitat from erosion and inconsistent weather and flooding seasons. Erosion increases sediment load in the
water which muddies the water, affecting fish that rely primarily on eyesight, and coating fish eggs with sediment,
affecting the egg hatching. Erosion also affects marine fishes as the increased sediment load of rivers flows into
the ocean and covers nearby coral reefs killing the coral and forcing the fish that rely on the coral to find unaffected
reefs. Reading this forward will take approximately 4 minutes. During that time 240 acres of tropical
rainforest that took over 70 million years to develop has been destroyed forever. If the destruction of the tropical
rainforests proceeds at its current rate of over one acre per second, the forests will disappear within the span
of a human lifetime. When these precious forests are gone, many of their treasures, both discovered and undiscovered,
will be lost. The tropical rainforest and its species are unique and irreplaceable; once they are gone humanity
will have nothing but regrets for these species will be gone for all time.
Dams are another factor that hurt
fish populations. Dams flood out rivers, streams, and creeks into one large lake. Often this lake floods forests permanently,
causing the vegetation to decay and altering the water conditions. Species that have adapted to river-life
must adapt to the altered conditions, or perish.
The dam prevents the upstream migration necessary for some species
to spawn. Examples of the loss of fish species after dam construction can be found in the Aswan Dam on the
Nile and the Amistad Dam on the Colorado.
Many countries, including our own, continue to dam rivers having biologically
Pollution is another destructive
factor produced by human use of river systems.
The effects of pollution range from the subtle, slow impact of sediments
from agriculture to the dramatic devastation of chemical spills that can destroy river systems For example, a recent
cyanide spill on the Essequibo River of Guyana decimated the local fish population and threatened large animal
life. Similarly, a few years ago, an oil slick on the Rio Napo in Ecuador dealt a blow to the delicate
ecology of one of the most biodiverse regions on the planet.
Less dramatic human activity can
have a significant impact on local fishes.
For example, the introduction of alien fish species into a water source
can be very destructive to the native fish population.
The introduction of the Nile Perch (Lates niloticus) as a food fish into Lake
Victoria has led to the extinction of several Haplochromine species and threatened virtually all other fish species
of the lake. Fish species can be introduced for reasons other than supplying food. The waterways of parts of Florida are
over-run by foreign fish species which have been released by fish keepers who have become bored with their pets
or have been overwhelmed by the size of the fish.
Less than 10% freshwater tropical
aquarium fish caught in wild. Overfishing for the hobby is not a major cause of declining fish populations, though some
species have been affected by over-collecting.
For example, some native collectors near Iquitos, Peru report that
catches of aquarium-bound fish are smaller than in the past. Commercial fishing for food fish is the main
cause to over-fishing. Throughout the Amazon, food fish are in lesser numbers and smaller in size than in the
past. For example, the Arapaima--which earlier was regularly found to exceed 10' (3 m)--is rarely encountered
today at a size greater than 8' (2.45 m).
Each aquariast needs to be aware
of the conditions that affect the natural environments which are the source of the wide variety of fishes that
are available today. We should all work to preserve the natural world, which not only makes possible our hobby,
but also supports the human species.
By Rhett Butler
New report: Global Warming is harming Lake Tanganyika fish