Introduction: Alga (Pl. algae) can be defined as, the primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems, roots and leaves. With a little bit more explanation algae can also be defined as: Algae are very large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. Most are photosynthetic like plants and simple because they lack the many distinct cell and organ types found in land plants. The largest and most complex marine forms are called seaweeds.
Algae are used for human betterment in a number of ways. These are used as food, fuel, bio fertilizer, stabilizing agent, for production of useful compounds, as bio filters to remove nutrients and other pollutants from waste water, to assay water quality, as indicators of environmental change, in space technology, and as laboratory research systems. Moreover, in small scale aquaculture to maximize cost-effectiveness it would be better to utilize locally available materials, either as ingredients (raw materials) in compound aquafeeds or as sole feedstuffs and on this aspect algae is highly acceptable.  Rather than, algae play a very important role in aquatic ecology as primary producer thus taken by fish as natural food. Thus we may say that, as algae are used by fish as natural food so it can also be used as fish bait. In Bangladesh, ant larvae, frog, trash fish, bread, earthworm, oil cake, mixture of wheat and husk, artificial bait, larvae of wasp, bee, etc. are generally used as bait by both hobbyist and fishermen. All these baits are used for herbivore, carnivore and omnivores. But, now, beside these it is found that local fishermen of Bangladesh at certain area use bunch of algae as fish bait to catch herbivore, fish.
Use of algae as bait at Dharla River,Kurigram: The Dharala River is one of the trans-boundary rivers of Bangladesh. It originates in the Himalayas where it is known as the Jaldhaka River, and then it flows through the Jalpaiguri and Cooch Behar districts of West Bengal, India, one of the seven main rivers to do so. Here the river enters Bangladesh through the Lalmonirhat District and joins with the Jaldhaka River and flows as the Dharla River until it empties into the Brahmaputra River near the Kurigram District. Near Patgram Upazila, it again flows easternly back into India. It then moves south and enters Bangladesh again through Phulbari Upazila of Kurigram District and continues a slow meandering course. 
Local fishermen of this river at Kurigram use bunch of algae as bait to catch herbivore fishes through angling. Angling is done in water areas of maximum 2 feet depth. Although such type of angling takes place all the year round but particularly at the end of winter such angling becomes intensify by the fishermen. Generally morning and evening are chosen for angling. This bait is not used with other bait. Fishermen usually collected algae from riverside stones or from other substrates. It seems that, the algae may be Spirogyra sp. After collection they make a small bunch of algae which is set on hook and then they get ready for angling. Kalibaus (Labeo calbasu) is the primary target.
Advantages of using algae as bait:
- Easy availability as it naturally grows on riverside. Artificial bait, ant larvae, larvae of wasp etc. are not available all time easily like that.
- No need to buy. Per kg ant larvae is sold at a rate of BDT 350-400/kg whereas larvae of wasp is about BDT 400-500, thus it is useful particularly for poor fishermen
- Fishermen especially hobbyist, get an opportunity to get rid of troublesome work of carrying bait.
- Easy to use, need not any preparation to use this bait. It is seen that, ant larvae; a popular fish bait requires careful preparation before use.
- Even housewives can use this bait in homestead ponds.
- Algae is natural to water, thus it would be more recognizable to fish than other baits.
- In case of foreign countries, the capture, culture and transportation of bait fish can increase damaging organisms between ecosystems, endangering them. In 2007, several states of USA, including Michigan, enacted law designed to slow the spread of fish diseases, including VHS (Viral Hemorrhagic Septicemia) by baitfish.
Disadvantage of using algae as bait: Not effective for carnivore fishes.
A General discussion on use of algae as fish bait: No literature is found on this topic by the author. But some other evidences helped me to conclude that, algae can be used as fish bait. Tiffany stated that: ‘Taxonomic botanist do not hesitate call wheat and corn and even bamboo ‘grasses’ but we are not allowed to include the algae, why? Well, it seems that a plant must have certain characteristics-grass characteristics, if you please-before it can be a grass seed, grass leaves, grass stems, grass flowers and grass roots. Algae have none of these. On the other hand, algae are to fishes and other aquatic animals what grasses are to horses and cows and giraffes.’ Some evidences show that, various algae and higher aquatic plants are exploited by fish and plant eating fish can survive on plants for food.  For any herbivore fish algae are the primary source of natural diet. In terms of preference, it is seen that, fishes take algae more than fishmeal.  Different species of herbivore fish are eligible to combat against algae.  In an experiment, both Tilapia aurea (Tilapia) andIctiobuscyprinellus (Bigmouth buffalo) show a FCR value of 2.00 feeding on algae. So we may conclude that, as algae is natural food and preferred by the fishes and it is found that at Dharla River, Kurigram it is practically used by fishermen. So, algae can be used as fish bait successfully for herbivores, sometimes for omnivore but never for carnivore.
Conclusion: Although different types of fish baits are used in Bangladesh, but if we consider the advantages and disadvantages, then it seems that, for herbivores algae baits are excellent. Most of the fishermen of our country are poor, this will be helpful for them .Such new type of bait can also attract hobbyist and may can contribute to the development of game fishing in our country. At last, as no literature is found on such topic, thus, it would be wise for us to collect such different types of information for the root level farmer and fishermen and other associates.
- Dr. M. Mahfujul Haque, Professor, Department of Aquaculture, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh.
- Dr. Zoarder Faruque Ahmed, Professor, Department of Fisheries Management, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh.
- Sheikh Mohammad Sayem, Lecturer, Department of Agricultural Statistics, Faculty of Agricultural Economics & Rural Sociology, Bangladesh Agricultural University, Mymensingh, Bangladesh.
- Fahmida Wazed Tina, PhD Research Student in Ecology and Biodiversity, Walailak University, Thailand
- Golam Rabbani, Faculty of Agricultural Economics & Rural Sociology, Bangladesh Agricultural University, Mymensingh, Bangladesh
- Haque MM (2012) Fisheries and Aquaculture Dictionary, first edition. Department of Aquaculture, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh. p. 13.
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