Featured Research

from universities, journals, and other organizations

Discus fish parent young like mammalian mothers

Date:
November 1, 2010
Source:
Journal of Experimental Biology
Summary:
Most fish abandon their young at hatching, but not discus fish. Researchers have discovered that discus fish parent like mammalian mothers. Not only do the parents feed their young from mucus secreted on their surfaces, but the nutritional and immunological content of the mucus changes as the young develop, much like mammalian milk.

One colored discus fish. Discus fish young feed on the mucus that their parents secrete over their bodies until they are big enough to forage.
Credit: iStockphoto/Artem Rudik

Few fish are famed for their parenting skills. Most species leave their freshly hatched fry to fend for themselves, but not discus fish. Jonathan Buckley from the University of Plymouth, UK, explains that discus fish young feed on the mucus that their parents secrete over their bodies until they are big enough to forage. 'The parental care that they exhibit is very unusual,' says Buckley. Intrigued by the fish's lifestyle, Buckley's PhD advisor, Katherine Sloman, established a collaboration with Adalberto Val from the Laboratory of Ecophysiology and Molecular Evolution in Manaus, Brazil, and together with Buckley and Richard Maunder set up a colony of breeding discus fish to find out more about their strange behaviour.

The team published their discovery that discus fish parent their young like mammalian mothers on 29 October 2010 in The Journal of Experimental Biology.

Unfortunately, discus fish are notoriously difficult to bred and keep in captivity. 'Hobbyists didn't succeed in rearing them until the 1970s,' explains Buckley. Having imported 30 adults from breeders in Malaysia, the team reproduced the breeding conditions in the Amazon during the dry season to encourage the fish to spawn. They lowered the water level and left it for a few hours before topping the tank up with cold water, and repeated the process until the pair was ready to lay their eggs. Buckley also collected samples of the orange mucus from the fish's flanks before they spawned and at various stages after the eggs had hatched, and monitored the parent's behaviour as their offspring grew.

During the first 3 days after hatching, the fry remained attached to the cone where the parents laid their eggs, absorbing the yolk and gaining strength until all of the fry were able to swim independently. Then they left the cone en masse and began feeding on their parents' mucus, feeding for up to 10·min by biting at the parent's side until the parent expertly 'flicked' the shoal over to its partner to continue feeding. The parents diligently fed their young intensely for 2 weeks. However, 3 weeks after hatching the parents' behaviour began to change as they started swimming away from their young for brief periods. At the same time the fry began biting their parents less and investigating other food sources. By the fourth week the parents were actively swimming away from their brood for the majority of the time and the fry barely bit them at all.

'There are a lot of parallels between the discus fish's parental care and the parental care that we see in mammals and birds,' says Buckley. Initially the parents invest all of their effort in raising their current batch of young, but wean the offspring when their investment in the current brood might begin affecting later broods. Buckley suspects that he sees signs of the conflict often seen between mammals and their young -- where parents want to wean their offspring and the offspring continue pursuing them -- in the fish's chasing behaviour during the third week after hatching.

Monitoring the composition of the parents' mucus before they spawned and through to the end of their parental responsibilities, Buckley found a huge increase in the mucus's antibody and protein levels when the parents laid their eggs, similar to the changes seen in mammalian milk around the time of birth. The protein and antibody levels remained high until the third week and returned to pre-spawning levels during the fourth week after hatching. Buckley suspects that the sudden increase in protein levels at spawning is hormonally regulated, much like the changes in mammalian milk, and is keen to find out more about the hormones that regulate the fish's mucus supply as they care for their young.

This research was funded by the Leverhulme Trust.


Story Source:

The above story is based on materials provided by Journal of Experimental Biology. The original article was written by Kathryn Knight. Note: Materials may be edited for content and length.


Cite This Page:

Journal of Experimental Biology. "Discus fish parent young like mammalian mothers." ScienceDaily. ScienceDaily, 1 November 2010. <www.sciencedaily.com/releases/2010/10/101029104603.htm>.
Journal of Experimental Biology. (2010, November 1). Discus fish parent young like mammalian mothers. ScienceDaily. Retrieved August 22, 2014 from www.sciencedaily.com/releases/2010/10/101029104603.htm
Journal of Experimental Biology. "Discus fish parent young like mammalian mothers." ScienceDaily. www.sciencedaily.com/releases/2010/10/101029104603.htm (accessed August 22, 2014).

Share This




More Plants & Animals News

Friday, August 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) — An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Newsy (Aug. 21, 2014) — According to a new study, spiders that live in cities are bigger, fatter and multiply faster. Video provided by Newsy
Powered by NewsLook.com
Lost Brain Cells To Blame For Sleep Problems Among Seniors

Lost Brain Cells To Blame For Sleep Problems Among Seniors

Newsy (Aug. 21, 2014) — According to a new study, elderly people might have trouble sleeping because of the loss of a certain group of neurons in the brain. Video provided by Newsy
Powered by NewsLook.com
Ramen Health Risks: The Dark Side of the Noodle

Ramen Health Risks: The Dark Side of the Noodle

AP (Aug. 21, 2014) — South Koreans eat more instant ramen noodles per capita than anywhere else in the world. But American researchers say eating too much may increase the risk of diabetes, heart disease and stroke. (Aug. 21) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins